A program is a passive entity(是被动的主体),such as a file containing a list of instructions stored on disk(often called an executable file(就是可执行文件))
A program becomes a process when an executable file is loaded into memory.(可执行文件中的指令一条一条加载进内存,成为一个进程)
A process is an active entity(进程是活动的实体),with a program counter(程序计数器,就是pc寄存器) specifying the next instruction to execute an set of associated resources.(一个程序加载进内存变为一个进程,也需要先把第一条指令写入到pc寄存器中,才可以被执行)