The first paragraph of the text deals mainly with the earth atmospheres______.
A．sheltering effect
B．reviving effect
C．invigorating effect
D．cleansing effect

A.
A．sheltering
B.reviving
C.invigorating
D.cleansing

【参考答案】

A
属主旨思想题，考查第一段的内容概括。第一段主要介绍大气层是地球的保护者。