He told us that he was tired and thirsty because he ________ in the desert for days.

A．walked

B．has walked

C．had walked

D．would walk

以下关于long、inc和short类型数据占用内存大小的叙述中正确的是( )。

A) 均占4个字节
B) 根据数据的大小来决定所占内存的字节数
C) 由用户自己定义
D) 由C语言编译系统决定