()的筛孔较大,主要用于生产煤样的筛分实验。
A、电动振筛机
B、大筛分用筛
C、小筛分用筛
D、标准筛
参考答案:B
This is the second time I _____ by him ; I shall never trust him again. [ ]
A. was put down
B. have been let down
C. have been put down
D. am let down
引起继发性甲状腺功能减低症最常见的病因是()
A.希恩综合征
B.缺碘性地方性甲状腺肿
C.慢性淋巴性甲状腺炎
D.先天性甲状腺发育不良
E.甲状腺大部切除术后