接种卡介苗可以有效预防结核病，其作用机理是 [ ]

A．卡介苗能激活人体的吞噬细胞，将结核杆菌吞噬

B．卡介苗能使人在不发病的情况下，产生抵抗结核杆菌的抗体

C．卡介苗能够促进人体的各项生理活动，增强抵抗力

D．卡介苗进入人体后能直接消灭侵入人体内的结核杆菌

小题1:________ Betty __________ (study) in this school since she came here in 2008?

小题2: ---Must the children _____________ (teach) how to cook when they are at home alone?

---Of course. It is necessary for them to learn how to cook.

小题3:I didn’t catch what you said just now because I_________ (answer) a call from my aunt.

小题4:----Why did John look so unhappy?

----Because he _______________ (not reply) to his wife by the time he left for Paris.

小题5: Usually before exams, the students ____________(give) five minutes to write their names and read through the paper.

小题6:Simon ____________ (take) a lot of photos while he was in Shanghai. He will show them to us when he returns.

小题7:The weather report said that the bad weather ______________ (last) for two days. What shall we do?

小题8:Having the robot _______________ (do) all the housework is really great. I can get more free time for my hobbies.