进罐入塔分析结果有效期应为（）小时。A、1 B、2 C、3 D、4

试述定员的目的？

与细胞外游离病毒结合，阻止病毒吸附易感细胞的是

A．中和抗体
B．NK细胞
C．补体结合抗体
D．CTL
E．干扰素

用所给词的适当形式填空。

1. This is our _____ (twelve) lesson, Tom, please listen carefully.

2. Does the key ring belong to ______ (I)?

3. I think we need about 15 ______ (loaf) of bread.

4. We look forward to ______ (win) the match.

5. Each of you ______ (have) a nice bike, right?

6. I ask my brother ______ (run) along the street.

7. — _____ Mary ______ (visit) her grandmother next Friday?

   — Yes, she is.

8. Take the second ______ (turn) on the right.

9. Look! The children are laughing _____ (happy).

10. The _____ (cook) in the kitchen are cooking nice food for people.

第二代电子计算机的主要元件是晶体管。

将一个直径为6厘米的铁球熔化后铸成一个立方体，则立方体的棱长是（）

A.9/2

B.

C.

D.