根据作业现场的“五必须、五严禁”十大安全纪律规定，作业人员上岗前必须了解本岗位的（）
A.危险因素
B.生产指标
C.生产特点
参考答案：A
— Why didn't Tom give you one of his paintings?
— I didn't want one, but he would have given me one if I ____. [ ]
A. did
B. had
C. would
D. could
具有镇痛、消炎、降压作用
A．苦参生物总碱B．麻黄碱C．小檗碱D．莨菪碱E．汉防己总碱
