中央空调采用了变频控制由那些优点（）
A.启动电流减小了
B.节能了
C.消除了50/60Hz的影响
D.舒适性改善了
参考答案：A, B, C, D
根据句意填写单词。
1. The box is _ . You can put your books in it.
2. I'm sorry for being late, Mr Smith. I worked too late last night and o _ this morning.
3. It's _ of you to believe him. He never tells the truth.
4. We all know that comedies always have very good and surprising e
5. On April Fool's Day we can hear many different kinds of h
图例在采暖施工图表示（）。
A.方形补偿器
B.集汽罐
C.角阀
D.蝶阀
（）。