凝析油在地面上的相对密度低，一般小于（）。
A.0.80
B.0.886
C.0.91
D.0.93
参考答案：A
I went to see you last Saturday, _____there _____no one in the room.[ ]
A. but; was
B. but; is
C. and; was
D. and; were
救生照明线使用电源是多少伏？（）
A.220伏
B.380伏
C.6伏
D.9伏
