在当前目录/home/zheng下新建一个目录back，将当前目录改为back，在back下新建2个长度为0的文件text1、text2，然后把text2移到其父目录中并改名为file2.

A. That's all right.
B. Sure.
C. All right.
D. Here you are.

A. That's all right.
B. Don't worry.
C. How are you?
D. Have a good journey.

A. Thank you.
B. How do you do?
C. How are you?
D. Have a good journey.

A. You're kind, too.
B. The same to you.
C. Don't think so.
D. You're welcome.