物料提升机的架体的主要构件有底架、立柱、导轨和（）。
A.横梁
B.纵梁
C.悬梁
D.天梁
参考答案：D
He is going to show you _________ his school. [ ]
A. of
B. around
C. in
D. at
装置防冻的基本方法有哪些？
