题干
We were lucky to have survived the train accident. _____, the first and last car were smashed.
A：On top of thi
B：What was worse
C：As it wa
D：So it wa
答案(点此获取答案解析）
C
中，点
在
上运动，给出下列四个命题：
的体积不变； ②
⊥
∥平面
； ④平面
