夹具的制造工艺流程为（）。
A、备料-热处理-机加-装配
B、备料-机加-热处理-装配
C、备料-热处理-装配
D、备料-装配-机加
参考答案：A
American Indian languages, which differ widely, tended to group many units of meaning into multisyllabic words.()
A. all tend
B. and tend
C. to tend
D. tending
防护头罩的作用是保护头部免受（）的伤害
A.腐蚀性烟雾和粉尘
B.热辐射的伤害
C.火焰的伤害
D.细菌、昆虫
