单选题
The atmosphere consists of _________.
A、
contains a layer of ozone gases.
B、
about 42 degrees colder than on the ground.
C、
21% oxygen by weight.
D、
less than 1% of xenon by volume
E、
about 75 degrees colder than in Interlaken
F、
is warmed by the earth’s heat.
【正确答案】
D
【答案解析】
提交答案
关闭