焦炭在高炉中的哪种作用不能被其它燃料代替（）
A、供热剂
B、还原剂
C、骨架
D、渗碳剂
参考答案：C
. -I hear Huang Gang made an English speech at the graduation ceremony yesterday.
-______ , and ______.
A．So he did, so did I
B．So did he, so I did
C．So he was, so was I
D．So was he, so I was
在全天侯着陆当中，最重要的气象要素是（）。
A、跑道能见度
B、水平能见度
C、云
D、跑道视程
