制动轮发热,摩擦片很快磨损并烧焦的原因有()
A、制动轮工作表面粗糙
B、闸瓦与制动轮间隙不均匀或间隙过小
C、摩擦片太厚
D、主弹簧过紧
参考答案:A, B
下列各项中,哪一项不是深龋治疗的并发症()
A.充填后咬合痛
B.意外穿髓
C.充填体折断
D.髓腔壁穿孔
E.继发龋
Betty is going to London. But I don’t know ________.
A.when she sets off
B.when does she set off
C.when she will set off
D.when will she set off