由物件的自重通过偏心块和物件之间的自锁作用而产生夹紧力的夹具是()。
A.杠杆夹钳
B.偏心夹钳
C.他动夹钳
D.钢丝绳夹具
参考答案:B
We are not allowed ______ in public. [ ]
A. to wait in line
B. to pick up the litter
C. to smoke
D. to keep your voice down
下列哪项不是亚急性皮肤型红斑狼疮的皮疹特点()
A.位于暴露部位
B.愈后不留瘢痕
C.呈对称性
D.皮疹局限
E.病变表浅