袋牌可供人们识别袋内所装邮件的()等。
A.内装物品
B.种类
C.寄发局
D.接收局
参考答案:B, C, D
Many strange new means of transport have been developed in our century, the strangest of _____ being perhaps the hovercraft(气垫船).
A.which
B.them
C.that
D.it
以下哪些构件是落地式钢管脚手架搭设时所使用的构件()。
A、钢管
B、扣件
C、脚手板
D、底座