根据下面的对话情境，在空白处填上一个适当的句子，使得对话完整。

T: Hi, Long Yufeng! You look so sad. 小题1:                            ?

A: I failed the English exam.

T: 小题2:                    . But you don’t need to worried about it all the time.

A: I really don’t know how to study English well. 小题3:                        ?  

T: I think you’d better study in a group.

A: Oh, 小题4:                    . Could I join your group?

T: Of course you can. And we can learn from each other.

A: Sounds good. 小题5:                 ?

T: You can join it tomorrow, if you like.

A: That’s very kind of you.

氧化一还原反应的实质是反应物的被氧化元素和被还原元素之间发生了电子转移。