有补偿器装置的管道,在补偿器安装前,管道和固定支架()进行固定连接。
A.必须
B.应首先
C.可以
D.不得
参考答案:D
Was it because of the heavy snowstorm in Europe ________ the flight had to be put off?
下列给定的是纸盒的外表面,下列哪一项能由他折叠而成?
A.如上图所示
B.如上图所示
C.如上图所示
D.如上图所示