用括号内所给动词的适当形式填空。

1. When I entered the office, the boss stopped _____ (talk) with me.

2. In e-mail English, punctuation marks are used for _____ (show) feelings.

3. The host family did their best to make me _____ (feel) at home.

4. You're not supposed to eat or drink while _____ (walk) down the street.

5. All of the students _____ (suppose) to hand in their homework on time.

采用壳聚糖精制的方法（）

A．水提醇沉法

B．离心分离法

C．大孔树脂法

D．膜分离法

E．吸附澄清法