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As the title asks, why can't we use 2 conjunctions in a sentence? For example:

Because it is raining today, so I go out with umbrella.

It sounds correct in Chinese, but my teacher said that it's incorrect in English, without giving any reason.

Does anyone know the reason?

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Related: ell.stackexchange.com/a/22002/3281. – Damkerng T. Jun 9 '14 at 2:44
Thanks for linking! – haudoing Jun 9 '14 at 2:47
The answers below explain about the conjunction, but also you should use an article here: "It is raining today, so I go out with an umbrella." Also, it seems more natural to me to use either present continuous or past tense, as in either "am going out" or "went out". – Evan Donovan Jun 9 '14 at 13:35
up vote 23 down vote accepted

You can use many conjunctions in a sentence; but you have to use them the right way.

It's complicated, but here's a simplified explanation which handles the example you offer.

At clause level there are two sorts of conjunctions, which establish different relationships between the clauses they join.

  • a coordinating conjunction (Collins, so, 18-21 calls this a sentence connector) puts the two clauses it joins on the same ‘level’: each clause is syntactically independent.

    Just for example, let’s suppose that there’s a network in which the members are obliged to pass on interesting news.

      A so B

    Jim told Agnes, so of course she told me.

    In theory you can chain as many coordinating conjunctions as you want; the only limit to the number of clauses you can join this way is your hearer’s patience.

      A so B so C so D so E ...

    Harry told Louise, so she told Jim, so he told Agnes, so she told me, so I will tell Phyllis, so she will tell ...

    This is not good written style, but it is very common in oral storytelling.

  • a subordinating conjunction puts the clause it introduces at a ‘lower level’ than the clause it is joined to. That is, the clause introduced by a subordinating conjunction is not independent: it plays a distinct role within the other clause.

       because B

    Agnes told me because Jim told her.

    because Jim told her explains why Agnes told me.

    Again, there is no theoretical limit on how many subordinations you may chain A because B because C because D ...

    Agnes told me because Jim told her because Louise told him because Harry told her, because ...

    Each clause explains the clause ‘above’ it.

Now: you are free to combine coordinating and subordinating clauses to express complex relationships, as long as you keep the relationships straight.

      A          so C
       because B

Jim told Agnes because Louise told him, so Agnes told me.

But: what you cannot do is put two clauses in two different relationships to each other; and that is what your example does:

Because it is raining today, so I go out with my umbrella.

      A     so   B
       because A

When you use both a subordinating and a coordinating conjunction, A shows up twice in the diagram. The meaning is clear, but syntactically A is assigned two conflicting roles, which is a no-no.

Just by the way: your construction was acceptable in older English, down to about the middle of the 17th century; but it disappeared in the ‘rationalization’ of formal discourse which occurred after the Restoration.

Note, by the way, that although because is always a subordinating conjunction, so plays different roles in different contexts. In the examples above, it is a coordinating conjunction; in other cases it may act as a subordinating conjunction:

Because it is raining today I’ll take my umbrella so I don’t get wet.

English, as I’m sure you’re aware, is full of traps like this.

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CocoPop's answer was pretty good, but for a more formal answer:

A conjunction joins two sentences. In Chinese, from what I understand, the conjunction used here has two parts, but is one conjunction - the two parts must be used together.

The English conjunctions "because" and "so" are not two parts of one thing; each one is its own conjunction. SO when you use them together, you are doing the "job" of a conjunction twice, so it doesn't make sense.

Edit: As FumbleFingers points out in his comment, it is strictly speaking possible to use two conjunctions in one sentence; the problem is using them in one join.

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So you think you can't use both conjunctions because it doesn't make sense? But I think both that sentence and this one are fine, because in each case the two conjunctions have different referents. In both, the first conjunction relates to something preceding, outside the utterance (your answer, and my first sentence), and the second expresses the relationship between separate elements within the utterance. (But the general thrust of the answer is quite correct, obviously.) – FumbleFingers Jun 9 '14 at 13:39
@FumbleFingers: Many of my English teachers would have given you disapproving looks for both of those sentences, but for other reasons. :) They tend to frown on starting a sentence with a conjunction. – cHao Jun 10 '14 at 11:41
@cHao: But if they gave me disapproving looks I would spit in their eyes! When I got my degree 40 years ago, the only job I was qualified to start straight away was teaching English (a path which many of my fellow students took). Instead, I went into computing, which at the time had virtually no "specifically-qualified" new entrants. I can still finish a crossword quicker than most of those I still know who took up teaching, but few of them are much good at getting the most out of a home computer or the cloud. Mostly, they represent the past, not the future. – FumbleFingers Jun 10 '14 at 12:54

At first glance, it seems to throw off the cause-and-effect balance of the sentence by introducing a redundancy that is difficult for the (native) listener to parse. Also, it makes it hard to justify the otherwise elegant "tent" contour of a true cause and effect statement:

/because it's raining/ \I'll take the umbrella\


/it's raining today/ \so I'll take the umbrella\

With two conjunctions, they're just flat statements with no coherence:

-because it's raining today- ... -so I'll take the umbrella-

Not a very scientific explanation, just my personal impression.

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Thanks for answering! – haudoing Jun 9 '14 at 6:02
I second that, basically the sentence you posted does not make sense or shall I say a little weak, so just go for either one like the answer states – Scarl Jun 9 '14 at 10:28

"Because it is raining today" implies that you are about to explain what will or did happen. Adding "so" is redundant. You could also say "It is raining today so I will go out with an umbrella."

Also, note that you need to change the tense on the second part to "I will" or "I went".

Finally, while technically correct, most English speakers would not say "go out with an umbrella". Go out with usually implies a romantic date. They would say, instead:

Because it is raining, I will take an umbrella.

It was raining, so I took an umbrella.

Good luck learning English!

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