进程P1、P2、P3、P4、P5的前趋图如下。

若用PV操作控制进程并发执行的过程，则需要相应于进程执行过程设置5个信号量S1、S2、S3、S4和S5，且信号量初值都等于零。下图中a处应填写 (1) ；b和c、d和e处应分别填写 (2) ，f、g和h应分别填写 (3) 。

2（）

A．P(S1) 和P(S2)、V(S3)和 V(S4)

B．P(S1)和P(S2)、P(S3)和P(S4)

C．V(S1) 和V(S2)、P(S3)和 P(S4)

D．P(S1)和V(S3)、P(S2)和V(S4)

用所给单词的适当形式填空。

1. Yao Ming is a ______ (know) basketball player in the world.

2. There are a few ______  (play) over there. 

3. My grandfather is so ______  (love) that everyone likes him.

4. What can I do______ (become) famous?

5. He ______ (stop) playing football last month because of his sore back.