I often visit my parents, who live in the countryside whenever_______.

The students were ________ over the ________ problem，listening to the teacher with a ________ expression on their faces.

The records of S.H.E are____ being bought, for their songs can bring energy into us.

The witness was expected to give the police a           description of what had happened, but he was too scared to do any help.

------________ to many people’s expectation, the 2009 UN climate Change Conference didn’t achieve any specific goals. ------ Yes, it’s really disappointing.