They _______Sally and Bob. Sally _______mycousin.

下列各句中，没有语病的一句是(　　)

Only when class began ______that he hadleft his book at home．

Measures have been taken to clean up the lake,but it will be some time________the situation improves[ ]

does enjoy working in China. It’s sometimes _______ being away from his family, but people in China treat him with nothing but kindness.