Is Jenny skating?[ ]
A. Yes, Jenny is.
B. No, she is.
C. Yes, she is.
答案：C
_____ he wasn’t ready in time, we went without him.
A．Since
B．As
C．For
D．Because of
下列哪种物质是大气中的二次污染物？（）
A．SO2
B．H2S
C．CO2
D．O3
E．NO
