检查V带的松坚度时，用拇指以39N的力按V带中部，其挠度应为（）。
A.5~10mm
B.10~15mm
C.15~20mm
参考答案：B
已知y=f（x）在（-∞，+∞）上是减函数，且f（1-a）＜f（3a-1），则a的范围是______．
Lucy will keep her word and carry on with the project _______ it means losing a lot of money.
A．so that
B．as though
C．now that
D．even if
