I won't let you in (除非) you can provide a proper ID.
Doing sports can make people happier, (健康), and more confident.
Flying in the sky, we can see the fascinating city (在下面).
In the face of danger, all the firefighters were brave and (没有一个) of them gave up.
到目前为止,他还没有读完这本关于太空的书.(finish doing)
当我们不知道如何解决问题时,可以向老师寻求帮助.(how to…)