Scientists have found no ________of life on Mars so far,though great efforts have made on the research.

Reading provides quiet, peaceful time alone and can be a good _______ from your busy life.

Hard work is no     of an excellent school record．You have to adopt a flexible approach to your learning．

I shouldn’t have accepted the man’s present, but I found it difficult to turn down his ______.

He holds an important ______ in the company.