例句：

　　When should you prune apple trees?

　　蘋果樹應該什么時候剪枝？

　　Should police officers carry guns ?

　　警察應該佩槍嗎？

　　No income should remain undeclared.

　　一切收入均應申報。

　　The selectors should resign en bloc.

　　這些選擇者應該集體辭職。

　　You should have seen it!

　　你應該看見的！