委托人申请注册的商标可能存在《商标法》规定不得注册情形的，商标代理机构（）告知委托人。
A.无须
B.应当明确
C.可以
D.可选择性
参考答案：B
Go straight _____________ three minutes. [ ]
A. to
B. for
C. at
— The light in his room is still on. Do you know _________?
— To prepare for the coming exam, I think.
A．if he works hard
B．why he stays up so late
C．why is he so busy
D．when he will stop working
