允许速度vmax≤120km/h正线及到发线,钢轨为60kg/m,总磨耗超过()时,钢轨为轻伤。
A、10mm
B、12mm
C、14mm
D、16mm
参考答案:C
已知正比例函数y=f(x)=kx(k<0),用“<““>“符号连接:f(2)______f(3).
It was not until he became very ill ______ he went to see a doctor.
A.what
B.that
C.when
D.then