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【单选题】Space is a dangerous place, not only because of meteors (流星) but also because of rays from the sun and other stars．The atmosphere again acts 【C1】______ our protective blanket on 【C2】______ ．Light gets...
A.
for
B.
with
C.
on
D.
as
【单选题】Space is a dangerous place, not only because of meteors(流星) but also because of rays from the sun and other stars. The atmosphere again acts as our protective blanket on earth. Light gets through, and...
A.
The Atmosphere and Our Environment
B.
Research on Radiation
C.
Effects of Space Radiation
D.
Importance of Protection Against Radiation