为了保证三角带的工作面与带轮轮槽工作面之间的紧密贴合，轮槽的夹角应略小于带的夹角。
参考答案：对
to looking after her sick mother for two years,she badly needed a holiday.
A．Having devoted
B．Devoted
C．To be devoted
D．To have devoted
临床上出现黄疸时，总胆红素一般至少为（）
A.17.1μmol／L
B.20.1μmol／L
C.25μmol／L
D.30μmol／L
E.34μmol／L
