机械零部件的失效形式主要为()
A、变形
B、断裂
C、磨损
D、腐蚀
E、锈蚀
参考答案:A, B, C, D
— Tom doesn’t seem so enthusiastic as he was two years ago.
— Yes. He’s really reached a point in his career ______ he has to decide what to do next.
A.that
B.when
C.where
D.which
关防喷器时要果断,一次性关闭。