壁细胞内合成盐酸的部位是（）。
A、细胞内分泌小管
B、粗面内质网
C、线粒体
D、微管泡系统
参考答案：A
煤在溜槽中的阻力系数（）。
A、0.8—1
B、0.6—0.8
C、0.2—0.4
D、0.4—0.6
— Have you got the news about Jack? I haven't seen him for many years.
— He _____ in a company for two years. Now he is a teacher. [ ]
A. worked
B. has worked
C. had worked
D. would work
