根据句意及首字母提示补全单词，使句子完整正确。

1. Bob is a quiet boy. He feels nervous to speak in p_________ .  

2. I have a bad cold and I c_________ a lot.  

3. Don't b_________  the school rules when you are in the school.  

4. Who is the w_________  of the writing contest?  

5. My teacher e_________ me not to give up studying English.

有以下程序：
#include＜stdio.h＞
main()
int c=0，k；
for(k=1；k＜3；k++)
switch(k)
default:c+=k；
case2:c++；break；
case4:c+=2；break；

printf("%d\n"，c)；

程序运行后的输出结果是( )。

A．3
B．5
C．7
D．9