When I told her that our journey would begin _____ an altitude of more than 5,000 metres, she seemed to beexcited about it[ ]

periment has_________ the possibilityof the existence of any life on that planet, but it does not mean there is nolife on other planets

On no account _______ out of the reading-room.

We had a really bad time about six months ago but now things are ________．[ ]

下列各句中，表达得体的一句是（ ）