3.Waste paper ________________ (should throw) in the litter bins.

问题描述:

3.Waste paper ________________ (should throw) in the litter bins.
4.Plates and dishes _______________ (not wash) after supper yesterday.
6.____________ the box _____________ (may open) now,sir?

3.should be thrown 4.were not washed 6.May be opened