弹簧有哪些主要用途?
参考答案:
1.缓和冲击吸收振动
2.控制机构的运动
3.储存能量
4.测量力的大小
— Oh, it’s you. I__________ you. Why are you looking so thin and pale?
— I’ve been ill for weeks and still under treatment.
A.can’t recognize
B.could hardly recognize
C.haven’t recognized
D.wasn’t recognizing
下列用于中药提取液中药物分子分离的滤过方法是
A.微孔滤膜滤过
B.石棉板滤过
C.超滤法
D.垂熔滤器滤过
E.离心分离