He passed through a difficult period _____ after his marriage broke down. 

At first the institute refused to purchase(购买)  the  experiment  instrument,  but  this decision was ______ changed.

Having gone through several rounds of selection, the young man ______ gained a chance to perform in China Talent.

 The cousins are alike in age，but ________ they are as different as day and night.

-- Do you think it's a good idea to make friends with your students?-- ______, I do. I think it's a great idea.