In general, "should not" and "need not" have significantly different meanings.
"Should not" indicates that it is bad to do a particular thing. For example, you should not drive a car too fast, because driving too fast is dangerous.
"Need not" indicates that it is not bad not to do a particular thing (in other words, the thing is unnecessary). For example,...
You cannot use I haven't known that here. The present perfect describes a present state which arises out of a prior eventuality, and you are implicitly saying that your present state is that you do know that—which is not a state that can arise out of your previous ignorance. (It can emerge from your previous ignorance, but it can only arise out of learning ...
Being a teacher, she likes children.
When I read this, I assume:
1) The woman is a teacher. She teaches for a living.
2) She likes children.
3) There is some relationship between her love of children and her profession. The exact nature of the causality is unclear – perhaps she got into teaching because she likes being around children, or perhaps she's ...
The basic 'rule' is that a present perfect cannot be modified by a temporal expression which does not include the present (let's call this an NPT for 'non-present temporal'). Under this 'rule' you are quite correct in thinking that the sentence would be better expressed with a past:
We saw them in 2008 and then again in 2010.
There are, however, two ...
The present perfect may be acceptable to some speakers of Standard English as it is used here, but not to others.
We very commonly use the present perfect to talk about finished past events that happened in a longer timeframe conceptualized as continuing into the present (this longer timeframe may be only implied): For example, those things might happen ...
If you say:
Being a teacher, she likes children.
you imply that she is still a teacher. You wouldn't say it if she were retired or had changed jobs.
Having been a teacher, she likes children.
means she was once a teacher but she isn't any more.
Answer edited to take J.R.'s comment into account.
In The English Verb Michael Lewis analyses pairs of sentences which are identical except that the verbs are in different tenses. This is what the OP's question asks us to do.
At the end of the discussion (p42) Lewis states:
Any difference in meaning between the two sentences of a pair is,
therefore, not something that we can decide objectively. The
You are quite right. This sentence does not belong in a discussion of the go VERBing construction. The sentence which should replace it is
I’ve never gone sailing.
Note, however, that this is an editorial mistake, not a grammatical one. The sentence “I've never been sailing” is both idiomatic and formally grammatical. With never, have ...
As OP has correctly understood, I worked 20 years in the software industry strongly implies that you no longer work in that industry.
But that doesn't mean I have worked 20 years in the software industry strongly implies that you still work in that industry. Perhaps you do, perhaps you don't. Without further context, it's meaningless to discuss whether ...
As Phil14 mentions in his comment, "you shouldn't have ..." has a note of reprimand, but this can vary with context:
You shouldn't have brought donuts, I'm on a diet.
(mild reprimand, equivalent to "I wish you hadn't done that")
Hey, you brought donuts! You shouldn't have!
(zero reprimand, equivalent to "Thanks!")
"You needn't have" can also ...
One obvious difference between the two sentences would be that phrases starting with words like "... when ..." are easily added to the past perfect version, but less so the simple past version:
"She had been in labour for 3 hours when her husband fainted for the first time."
Another thing is that the past perfect version puts more of an emphasis on the ...
The key lies in understanding the past perfect and the form is had + past participle.
The past perfect is considered as an early past. We go back for a moment whilst we are already talking about the past to clarify that something had already happened at that time we are talking about.
When I arrived at the party, Jane had gone.
Now think about that ...
Your answer is grammatically correct, so it is not wrong, but it is not the best of the two answers. Here's why:
I did not know about it.
This establishes that we're talking about something in the past – a time when you did not know something. (Clearly, you know about it now, because you're talking about it!)
Now imagine that you say the second sentence ...
Just would like to know if we could write "What had happened while we were away" . I think past perfect is not obligatory in time clause.
You are correct, "were away" will do. Apart from being understood, there are some nuances.
The story is about what they found when they returned from vacation, that is, what had happened while they were away. They ...
As you say, the first sentence has no grammatical error.
If that is the entire question, the test is badly designed. Perfect constructions are used to establish temporal reference relative to the discourse context. But there is no context here, so there is no evident reason to pick one or the other.
This is fairly confusing in that "should not do" and "need not do" are not equivalent negations of "should" and "need".
"Need not do" is as you would expect, the opposite of "need to do" - "not need to do". These things are the opposite of a requirement and are therefore optional.
However "should not do" is much closer to a positive requirement ("...
When a single event in the past happens, simple past is fine.
When I went into the room, the vase was broken. What happened to it.
In your example:
What had happened while we had been away?
the burglary happened over a period of time in the past. They had to enter, search, take things and leave. The additional text confirms this:
A burglar had ...
Yes, you can put a perfect construction after since, but the first example seems slightly clumsy.
Normally you would say:
It's been a long time since I last saw your face.
It might be an attempt to be artsy, but unlike most violations of grammar in poetry or song, this doesn't sound deliberate to me. I think it's just a sloppy but acceptable analogy ...
Present perfect is usually used if you want to emphasise what happened rather than when. (eg: Headlines).
So yes, broadly speaking I would probably say I have heard....
It doesn't necessarily mean that I have heard it many times though , maybe I just can't recall when.
Past simple is always used when you specify the time when something happened , even ...
I don't think we can use past simple here. It's not (in my opinion) a question of ambiguity. The reason is this: we're referring to a very specific "had done", which is "what he had done to solve this great problem". Therefore, "understand what he had done" allows the reader to immediately understand we are talking about the solution he devised, rather than ...
A non-finite clause might better be defined as a clause headed by a non-finite verbform: an infinitive or a participle. Such a clause by definition1 has no tense. It cannot be the main or matrix clause in a formal sentence, because a matrix clause must be headed by a finite verbform, which defines its Reference Time—the time you are talking about. (see ...
This might be a bit nit-picky, but I don't think this means quite what you want it to.
This tree has stood here for many years.
The tree began standing there at one point, and continued to stand there, without interruption or change, for many years. That makes sense.
We have broken this rule for two years.
So similarly to the tree example, this would ...
A good starting point is Laura Michaelis' chapter on “Time and Tense” in Bas Aarts and April McMahon, eds., The Handbook of English Linguistics, Oxford, 2006. The chapter is available online here.
It should be noted, however, that technical treatments of this sort are way beyond what any ‘Master’ of the language, in the sense ...
Yes, they're grammatically correct.
No, they aren't redundant. The "extra" haves are not "extra" at all; they're used to put the verbs into the present perfect. I'll try to explain each verb one at a time:
First, let's break down the first clause:
I would have1 had2 to have3 played4 an unbelievable match
have1 and have3 are both auxiliary verbs. In ...
Both sentences are different. The comparison should be something like
(1) The car isn't starting.
(2) The car hasn't been starting.
However, these are quite different.
Present continuous is used for action happening right now. (Not in the past.)
The car isn't starting.
Present perfect continuous is used for an event that began in the past and is ...
"have had to" and "had had to" are the perfect forms of "have to"/"has to"/"had to", so it operates very similarly to the difference between the simple and perfect in other cases:
I have to eat before noon
I have had to eat before noon every day this week
The first is an obligation one time; the second specifies a recurring obligation ...
Your understanding of the three phrases is not quite correct:
has gone to - there or on his way to;
has been to - someone has been there but he is on his way back; OR someone has been there at some point in the past and is now elsewhere
has been in - someone is still there; someone has gone there at some point in the past and is still there
So these ...
As always, the choice of the perfect does not necessarily have a specific meaning.
It has the general meaning "This is a past event with present relevance", but the specific kind of present relevance can vary.
It might be that the activity is continuing into the present:
He's been cleaning that room for hours.
It might be that the activity has only ...