下列哪项是原始大气中没有的 [ ]
A．氢
B．氧
C．水
D．氨
B
— __________________ now?
— It's two o'clock. [ ]
A. What the time
B. What's the time
C. What time it is
D. Which time
堆栈段寄存器是（）
A.DS
B.SS
C.ES
D.CS
