Is or Are (Visiting customers and listening to them is/are the basis for...)

[Van Khanh]

Hello,

Please read the following sentence:

Visiting customers and listening to them is / are the basis for (the) improvement of products or creating new ones.

Please correct the above sentence.

( Should I use "is" or "are" ? Can I remove "the" ? What is the differences beetween "for improvement of products" and "for the improvement of products" ?)

Thanks

Khanh

[Edison_Chen_e_c]

I think it fine to use both of is and are. But it depends.

<cf>:
My mom passed away, and at the very moment any sympathy and cooperation is/are needed. (Take the sympathy and the cooperation as one, meaning if I got your sympathy, then I got your cooperation, if I got your cooperation, then I got your sympathy.)

Reading and swimming are needed for a student. (not 'is' here since reading and swimming are totally two different things talked about.)