[单项选择]建筑构件耐火极限是指：（）
A. 指对一建筑构件按时间一温度标准曲线进行耐火试验，从受到火的作用时起，到失去支持能力或完整性被破坏或失去隔火作用时止的这段时间，以天计
B. 指对一建筑构件按时间一温度标准曲线进行耐火试验，从受到火的作用时起，到失去支持能力或完整性被破坏或失去隔火作用时止的这段时间，以分钟计
C. 指对一建筑构件按时间一温度标准曲线进行耐火试验，从受到火的作用时起，到失去支持能力或完整性被破坏或失去隔火作用时止的这段时间，以秒计
D. 指对一建筑构件按时间一温度标准曲线进行耐火试验，从受到火的作用时起，到失去支持能力或完整性被破坏或失去隔火作用时止的这段时间，以小时计

给定程序的功能是：从键盘输入若干行文本(每行不超过80个字符)，写到文件myfile4.txt中，用-1作为字符串输入结束的标志。然后将文件的内容读出显示在屏幕上。文件的读写分别由自定义函数ReadText和WriteText实现。
注意：部分源程序给出如下。
请勿改动主函数main和其他函数中的任何内容，仅在行线上填入所编写的若干表达式或语句。
[试题源程序]
#include＜stdio.h＞
#include＜string.h＞
#include＜stdlib.h＞
void WriteText(FILE*)；
void ReadText(FILE*)；
main（　）

FILE*fp；
if((fp=fopen("myfile4.txt"，"w"))==NULL)

printf("open fail!!/n")；exit(0)；

WriteText(fp)；
fclose(fp)；
if((fp=fopen("myfile4.txt"，"r"))==NULL)

printf("open fail!!/n")；exit(0)；

ReadText(fp)；
fclose(fp)；

/**********found**********/
void WriteText(FILE (1) )

char str[81]；
printf("/nEnter string with -1 to end:/n")；
gets(str)；
while(strcmp(str，"-1")!=0)

The food we eat seems to have profound effects on our health. Although science has made enormous steps in making food more fit to eat, it has, at the same time, made many foods unfit to eat. Some research has shown that 40 percent of cancer is related to the diet as well, especially cancer of the colon (结肠). Different cultures are more prone to get certain illnesses because of the food that is characteristic in these cultures. That food is related to illness is not a new discovery. In 1945, government researchers realized that nitrates (硝酸) and nitrites (亚硝酸盐), commonly used to preserve color in meats, and other food additives (添加剂), caused cancer. Yet these carcinogenic additives remain in our food, and it becomes more difficult all the time to know which things on the packaging labels of processed food are helpful or harmful. The additives that we eat are not all so direct. Farmers often give penicillin(盘尼西林) to beef and poultry(家禽), and because of this, penicillin has
A. trouble-making
B. color-retaining
C. money-saving
D. cancer-causing