通常情况下,100L空气中氧气占 请选择DCBA:J(M.g1v,e'Q2v.M7P5e7A-Q;}8f*}(i5v6P3H(K*L
A.21L5e7A-Q;}8f*}(i5v6P3H(K*L
B.78L5e7A-Q;}8f*}(i5v6P3H(K*L
C.21g5e7A-Q;}8f*}(i5v6P3H(K*L
D.21T5e7A-Q;}8f*}(i5v6P3H(K*L