治疗肝火犯肺，灼伤肺络，咳嗽痰中带血，常以海蛤壳配伍的药物是（）
A.瓜蒌
B.贝母
C.郁金
D.青黛
E.知母
参考答案：D
. Tom as well as his classmates __________ a song when the teacher came into the classroom.
A．are singing
B．were singing
C．is singing
D．was singing
ν≤120km/h时，相邻吊弦高差的标准值不大于（）。
A、10mm
B、20mm
C、30mm
D、50mm
