风力（）以上天气应停止易产生扬尘的作业．严禁从建筑物内向外抛扬垃圾。
A.三级
B.四级
C.五级
参考答案：B
In China, students ____ greet the teacher when classes begin.[ ]
A. are supposed to
B. are suppose to
C. suppose to
D. is supposed to
患者被毒蛇咬伤5小时，局部微肿，伴头昏眼花，视物模糊，声音嘶哑，胸闷恶心，四肢麻木，舌淡微颤，脉弦数。其证型是
A．湿毒B．风毒C．火毒D．热毒E．风火毒
