起吊时吊钩要垂直于重心,绳子与地面垂直时一般不超过30º。
参考答案:错
Next winter, _____ you will spend in Harbin, I'm sure, will be another exciting holiday.
A.which
B.when
C.in which
D.where
My favorite sports _______ volleyball and tennis. [ ]
A. is
B. am
C. are
D. be