Using the past perfect in a simple sentence

Question

My English grammar book ("English Grammar" by David Daniels and Barbara Daniels) describes the past perfect as follows:

The past perfect describes an event in the past and shows that it was still relevant at a later time.

The given example is the following one:

Mario had already arrived home when his mother walked in.

Is it possible to use the past perfect in a simple sentence?

Mario had arrived home.

I could use the present perfect ("Mario has arrived home.") and that sentence would mean Mario is still at home. What would I get from the simple sentence using the past perfect?

Answer 1

No. Apparently not. The relevance of Past perfect lies in the fact that it differentiates between the time frame of two events, when both of them happened in the past.

Example:

Before she left for her college, she had finished her lunch.

You can use After too. In the given sentence in your question,

Mario had already arrived home when his mother walked in.

it is understandable that Mario had reached home before his mother walked in.

BUT a simple,

Mario had arrived home.

is meaningless and unnecessary as you are not referencing before what event had he arrive home. You can use simple past here. Of course, if in a conversation it is relevant that you did it before some action you can use simple perfect like you cited. Like:

2nd friend: Where do you work now?

1st friend: I work in ABC company now-a-days.

2nd friend: Oh! I see. I had worked there. (It means he had worked there before he left that job)

So put it simply,

Past perfect is not used unless and until we are comparing the time frames between two events. You can read more on past perfect in English Page: Past Perfect Tense.

Answer 2

As Mistu4u points out, understanding the temporal reference of the simple sentence Mario had come home, in the past perfect, requires a context incorporating a past Reference time to which the Event time can be related.

However, you are mistaken in believing that this is not equally true of the simple sentence Mario has come home, in the present perfect.

To be sure, the present perfect tells you that Reference time is the same as Speech time, the time at which the sentence is uttered. But the bare present perfect sentence tells you no more about when the Reference time occurred than does the bare past perfect sentence. In both sentences, the tense constructions tell you the same thing: the relative temporal positions of Speech, Reference and Event times. In both sentences, you require additional context to understand how these three relate to the time at which you encounter the sentence.

That context may be provided by the immediate situation —if, for instance, the sentence is spoken in your hearing and you have reason to believe that speaker is narrating a present fact and not quoting another’s past speech. It may be provided by a date on an email or letter. It may be provided in the surrounding discourse, whether a conversation or a historical monograph or a work of fiction.

But both sentences require context to provide any more information than the relative temporal positions of the three syntactic times.