按规定，自给式压缩空气呼吸器钢瓶内的储气量应至少为()升。
A.500
B.1000
C.1200
D.1500
参考答案：C
My mother says I was born _______ the morning _______ May 1st, 1998. [ ]
A. in; of
B. in; on
C. on; of
D. on; on
掺杂的杂质和沾污的杂质是一样的效果。
