LEL是指有害气体的爆炸（）。
A.临界点
B.上限
C.下限
D.极限
参考答案：C
外寒内热型哮喘治疗首选方剂是()
A．苏子降气汤
B．小青龙汤
C．大青龙汤
D．麻杏石甘汤
E．三子养亲汤
---Are you getting a new car this year?
---You must be joking! I can't afford to pay my bills, ________ buy a new car.[ ]
A. let alone
B. or rather
C. leave alone
D. other than
