为避免几个进程可能同时对同一文件进行存取，用______和______语句可以对文件“锁定”和“解锁”。
参考答案：Lock；Unlock
根据首字母和汉语提示填入所缺单词。
1. There is a______(地图) on the wall.
2. She______(是) a very good teacher.
3. I have a new ______(钢笔).
4. Is this your______(夹克衫)?
5. I like eating______(橙子).
单项选择。
_______ the window, please. Tom! [ ]
A．Closed
B．Close
C．Closing
D．Closes
