I would like to know which of the following sentences is correct:
Translating and adapting texts for different audiences composes the key of this theory
Translating and adapting texts for different audiences compose the key of this theory
The word "texts" is related to both subjects, hence the doubt. Lastly, is the use of for in "for different audiences" correct as well?
Non-finite clauses take singular agreement, so "composes" is correct. The fact that the subject has a coordination of two VPs makes no difference -- it's a single clause and as such takes a singular verb. Compare, by contrast, "Skating on the lake and swimming in the stream" are my favourite activities, where there is a coordination of two separate clauses, requiring a plural verb
Further, what composes the key of this theory is the combination of the two actions, not each of them individually, so a singular verb is usual. It is not the equivalent to the clausal coordination in, say, "Translating texts for different audiences and adapting suitable texts", where the expected verb would be a plural one.
— BillJ comments from 2019-04-12.
If the act of "translating" is part of the act of "adapting", then these two are considered as one action, and therefore, you use "composes".
If "translating" and "adapting" are two separate processes for your intended work, then they should be treated as separate actions, and therefore, the verb "compose" should be used.
--The use of "for" is acceptable in this sentence.
--Consider using "the" before texts, if you have already referred to these "texts" and/or you have defined the types of these texts.
