由直径不同的若干单一管道串联而成的输气管道称为().
A.复管
B.副管
C.变径管
D.串联管
参考答案:C
词汇运用
Do you know Hello Kitty? Children all over the __1__ (世界) all like her. She is a __2_ (可爱的)
girl. She__3_ (居住)in London, so she can speak English. There are__4__ (四) people in her family.
They are her mother, her _5__ (爸爸) and her sister. Her mother loves __6__ (煮) and she likes
making friends. A_7__ (狗) named Judy is her friend. Her favorite subject is__8__ (音乐). Look! It is
a __9_ (晴朗的) day. She is playing the __10_ (钢琴) in the park. She wants to be a pianist.
联轴器可兼作()装置。
A.永久连接
B.滑动连接
C.安全保护
D.轴上零件定位