脚手架各拉结点可垂直距离不应大于（）m。
A.2
B.3
C.4
参考答案：C
—Hurry up, please!
—It's quite early, you _____ worry about the time. [ ]
A. mustn't
B. may not
C. needn't
D. can't
甲基硫氧嘧啶抗甲状腺作用是通过抑制过氧化酶，影响( )环节起作用
