1.夏天长时间暴露在阳光下是有害的。
     It’s ____________ to be ____________ to the sun for a long time in summer.
2.这种药物尚未进行过人体试验，所以还不能投放到市场。
     This drug has not been ____________ ____________ on humans yet, so it cannot be put on the
market.
3.他所说的话未必意味着现在的工作就是他最喜欢的。
     ____________ he said does not ____________ mean that the present job is his ____________.
4.因为不习惯城市的生活，老人又回到了农村。
     ____________ ____________ ____________ to the life in the city, the old man came back to the
countryside.
5.负责行李的那个人在每件行李上都贴上了一个标签。
     The man in ____________ of the luggage ____________ a label to each piece.
6.该店由于正在修理屋顶，所以今天停止营业。
     The shop is ____________ today because the roof is ____________ ____________.