题目内容：

阅读下面短文，从短文后的五个选项中选出能填入空白处的最佳选项。每个选项只能用一次。

A robot teacher

Robots are smart because they have computer brains. They can help people work in dangerous places. 1.________. Brine, the robot mail carrier, brings mail to a large office building in Washington, D.C.. He is one of 250 robot mail carriers in the United States. But have you ever heard about a robot teacher?

Mr. Green is a fourth grade robot teacher. 2.________. One advantage is that he does not forget details. He knows each child’s name, their parents’ names and what each child knows and needs to know. 3.________. Mr. Green does not make mistakes. Each child goes and tells him his name, then dials an ID number. His computer brain puts the child’s voice and number together. He identifies the child with no mistakes. Then he starts the lesson.

4.________. If the children need more time to do their lessons they can move switches and change the timetable. In this way they can repeat Mr. Green’s lesson over and over again. When the children do a good job, he tells them something interesting about their hobbies. At the end of the lesson the children switch Mr. Green off.

The children like Mr. Green very much. 5._______. And when they make a mistake, they don’t feel upset. They have a lot of fun with a robot teacher.

A. They can also do difficult jobs B. He has some advantages as a teacher C. They feel happy and relaxed in his class D. He even knows each child’s pets and hobbies E. Another advantage is that Mr. Green is flexible (灵活的)