焊件因焊后两端翘起的变形称为______。
A.弯曲变形
B.角变形
C.扭曲变形
D.收缩变形
参考答案:A
—Where're the children, Mr Black?
—Oh, they _______ their PE lesson on the playground. [ ]
A. have
B. had
C. are having
D. have had
鞋分成雨鞋、凉鞋、运动鞋等时,是按()作为其分类标志的。
A.原材料
B.生产加工方法
C.用途
D.主要成分