What's in the classroom?
There are some desks and some chairs.
这样问答对吗？

对啊。不管回答是单数还是复数，都问what's in/on/near the    ?

There is no knife and fork on the table.    句式中的"no---and ---"是不是有问题的以前常常强调"no--- and no --- "就等于"no---or ---"的,不可以说"no---and ---"