接发列车时,必须站在()规定地点。
A、《技规》
B、《行规》
C、《站细》
D、《段规》
参考答案:C
Mr. Brown _____ go to bed early, but now he ____going to bed early.
A.used to, used to
B.used to, is used to
C.is used to, sued to
D.is used to, is used to
快中子是指中子能量大于()eV的中子。
A.5×104
B.5×105
C.5×106
D.5×107