_____60 miles a day，you need your mountain bike ina very good state.

The boy often tries his best ___________ his parents happy.

A new virus related to SARS is reported______ at leastone person in China last week.

a.gov.cn, which has _____foodand drug channel with clear explanations, is _____very popular website.

How much difficulty did you have_______ thisproblem -_______. It’s quite easy.