问题:
通常情况下,100L空气中氧气占
A.21L
B.78L
C.21g
D.21T
通常情况下,100L空气中氧气占
A.21L
B.78L
C.21g
D.21T
A.21L
B.78L
C.21g
D.21T
参考答案: