单项选择。
—Where you from? —I from China.[ ]
A. are; is
B. is; are
C. am; is
D. are; am
答案:D
——Did you know any French before you arrived in Washington?
——Never ____ it, actually.
A.had I learned
B.have I learned
C.I learned
D.was I learning
用机械矫正法矫正槽钢的变形时,为避免回弹的影响,应使槽钢在矫正时略呈反方向弯曲,()是确定反变形量的依据。
A.材料的强度
B.材料的塑性
C.回弹量
D.变形量