收缩量最大的材料是（）。
A.混凝土
B.水泥砂浆
C.水泥净浆
D.砂浆
参考答案：C
It wasn't such a good present ________ my cousin had promised me.[ ]
A. that
B. as
C. which
D. what
汽缸在工作时承受的作用力有哪些？
