用括号内动词的正确形式填空：

1. I'm ________ (wash) my clothes now, so I'm busy.

2. Why not _________ (buy) a newspaper to read now?

3. There _________ (be) a birthday party this evening.

4. My father is always ________ (forget) to wake me up.

5. As students, we must practice _________ (speak) English every day.

可编程控制器PLC的基本功能与特点是什么？