题目内容：
下面片段选自某高中英语课堂教学实录。T: Good morning, boys and girls. We talked aboutsome verbs yesterday. Now I’d like to see whether you have learned to use them.Are you ready?
Ss: Yes.
T: Listen! Yesterday, you were going to playfootball after school when it began to rain, so you didn’t do it. Can youdescribe it with the word “prevent”? Who would like to have a try?
S1: We didn’t play football yesterday because asudden rain prevented us.
T: OK. But would you please begin your sentencewith “The sudden rain…”? Who’d like to try?
S2. The sudden rain prevented us to playfootball yesterday.
T: Oh, you are so quick, and you are almostright. Do we say “prevent somebody to do something” or “prevent somebody…”
S3: Oh. The sudden rain prevented us fromplaying football yesterday.
T: Perfect. Let’s read S3’s sentence together andremember the verb pattern of “prevent”, OK?
根据该教学片段回答下面四个问题：
(1)该教师采取了什么方式引出复习巩固的内容？（5分）
(2)当该教师发现学生没有完全掌握所学内容时，采取了什么补救方法？(5分
(3)这种补救方法有哪两个优点？（10分）
(4)该教师复习巩固所教内容还可以采用其他哪两种方法？（10分）
答案解析：