If you don’t wait _______ the red light, you will be punished by the policeman.
A. at
B. under
C. in
D. on
从等强度出发,一对闭式软齿面齿轮,其齿面硬高应()。
A. HBS1>HBS2
B. HBS1<HBS2
C. HBS1=HBS2
D. HBS1≤HBS2
21、在下列齿轮的参数和尺寸中,属于标准值的是()。
A. 模数与分度圆直径
B. 模数与压力角
C. 压力角与齿距
D. 模数与齿数
Is there anything _____ I can do for you?
A. which
B. who
C. whom
D. that