求两平面的真实夹角，是将两平面的交线变换成投影面的（）。
A.倾斜线
B.平行线
C.垂直线
D.相交线
参考答案：C
根据句意、首字母提示完成单词。
1. Sam's favorite subject is ________ (物理学).
2. Please ________ (翻译) these Chinese sentences into English.
3. I want to i ________ my English, so I make friends with an American girl.
4. I can't go to the movies this Saturday. I have to have my piano l_______.
5. There are many t ________ visiting Beijing every year.
沉降体积比
