Scientist are not sure about the ___________ of water on the Mars.

 --- Where is the new dictionary? --- It’s on the top shelf, out of ______.

He can speak English, German, French and Japanese. He is nearly a man with a (an) ______ for language.

As she walked along a         , a door suddenly burst open, as though forced by someone behind it.

(2014·德州模拟)You’d better take into account your own________and weaknesses before choosing a major.