—Did your sisters go to the concert last night?—No, we               went to my aunt's birthday party.

(2013·重庆高考)Recycling is one way to protect the environment; reusing is ________.

Gradually, you will realize the things that matter are______that can’t be bought with money.

One of the students hasn’t prepared _____ lessons very well.

I would appreciate ________if you could come and help me with my work.