1. a. unsigned int
   b. float
   c. char
   d. unsigned int
2. 当系统中int的大小和long的大小相同时，使用int时应该改为long（可提高移植性），或者是当数据超过int的表数范围的时候应使用long

3.int32_t,确保在不同的系统中不会出现错误
4.
a.char backspace
b.int 数字1066
c.double 数字99.44
d.注意：unsigned int 十六进制常量
e.double 数字2.0x10的30次方
5.修改后的程序如下：

#include <stdio.h>
int main(void)
{
	float g,h;
	float tax,rate;
	g = .3e21;//注意，小数点和E可以省略一个不能同时省略，整数部分和小数部分可以省略一个但不能同时省略
	tax = rate * g;
}

//补充后的printf()
printf("The odds against the %d were %ld to 1.\n", imate, short);
printf("A score of %f is not an %c grade.\n", log, grade);

char ch;
=ch = '\r';//转移序列
ch = 13;//十进制
ch = 015;//八进制
ch = 0x0D;//十六进制

10.修改后的程序如下：

#include<stdio.h>
int main(void)	/*this program is perfect*/
{
	int cows, legs;
	
	printf("How many cow legs did you count?\n");
	scanf("%d", &legs);
	cows = legs/4;
	printf("That implies there are %d cows.\n", cows);

	return 0;
 
}

a.\n newline
b.\\ backflash
c." double quotes
d.\t horizontal tab