1.你确定这颗行星是安全的吗?
_________ ________ ________ this planet is safe?
2.他按了墙上的一个按钮,接着所有的灯都亮了.
He ______ a button _______ the wall, _________ _________ all the lights were on.
3.在高速路上开快车是非常危险的.
_______ is very dangerous ______ ______ fast on the highway.
4.我们的英语老师手里拿着录音机走了进来.
Our English teacher ______ ______ _______ a recorder in his hand.
5.你将会读到一个关于太空旅行的故事.
You ______ ______ ______ _____ a story about space travel.