In much of the animal world night is the time for sleep —pure and simple.A. set asideB.

问题补充：

In much of the animal world, night is the time for sleep —pure and simple.

A. set aside

B. set down

C. set off

D. set up

答案：

A. set aside

B. set down

C. set off

D. set up

解析：考查短语辨析。句意：在大多数动物的世界里，夜晚纯粹是留下来用以睡眠的时间。A搁置，留出；B记下，制定；C出发，动身，引燃；D建立，成立。根据句意可知答案选A，其他不符合语境

考点 :考查短语辨析