1 . Fountain pens ________________ (use) in schools long ago and have been regaining popularity lately because they are refillable. （所给词的适当形式填空）

2 . Investigating the way that dragonflies remain stable during flight actually ________________ (reveal) the techniques they use to get themselves out of tricky situations. (所给词的适当形式填空)

6 . These beautiful black­faced spoonbills are some of the world's rarest birds. The birds ________________ (fly) all the way from their summer home to this wetland, where they will spend the winter. Now, they circle and land. （所给词的适当形式填空）

7 . 生活中总有一些起起伏伏，但是正是苦难让我们更加坚强。
There are always some ups and downs in our lives, ________________. (强调句)

9 . 这是一个必去的地方，你到那里的时候，你会爱上它。(such...that...)
It’s ________________ when you go there.

10 . 登上山顶后，你可以欣赏到激动人心的风景，真是赏心悦目。(非限制性定语从句)
After reaching the top, you can enjoy________________.