"Họ mua không những máy tính mà còn điện thoại."

Translation: They buy not only computers but also telephones.

[CarolynCam11]

How do we know that the sentence refers to plural computers and telephones?

[SheTuti]

Because if using nouns without classifier (like here no cái/chiếc) the meaning is general, like computers, phones, devices...

[VianeyDubu]

not only buy should be correct

[martianalien]

Why is 'They buy not only a/the computer, but also a/the telephone' not correct here?

[nhxK6w]

Your sentence will be like " Họ mua không những MỘT cái..... mà còn MỘT cái...."

[martianalien]

using 'mot' would indicate 'a' rather than 'the'. My question is really about why we should assume that computers and phones here are plural, when there is no plural indicator. Usually Duo always wants us to say the+singular unless we have the word 'mot' for one/a or nhung/cac for plurality. Here the nhung is part of a nhung...ma construction, not a plural indicator, so I want to know what indicates plurality here, and therefore why singular nouns with 'a' or 'the' are incorrect. Incidentally, in practice you don't need to say 'mot' to indicate that you mean 'a' instead of 'the', though Duo usually wants you to do that.

[SheTuti]

I'm pretty sure now: classifier=the, một=a and almost every time you got the noun alone, it is a general plural... (hier máy is not a classifier, cái/chiếc would be). Please correct me if I'm wrong!

[SheTuti]

Please see comments above

[Steve804244]

Computer and phone can be singular or plural - it depends on the situation/context. The Vietnamese sentence does not make the situation clear. But Duolingo accepts only one arbitrary answer. You are playing a guessing game with the application.

[GinDaw]

Could DL, please, consider having the sentences read at different speeds. I have a translator that says it fast, then medium and then slowly. It's very helpful. Thanks