be able to的be可以换成is⼀was⼀am⼀were⼀are对吧

楼主你好~希望我的回答可以帮助到你>w<
1. be able to ，其中be的意思就代表系动词，即am/is/are, was/were。^-^楼主，对的哟
2. (tell)/(ask) sb. not to do，意思为要求某人不要做什么事。如果没写not, 那“不要”的意思就没有了，句子就不对哟~所以是要not的。

3. don't, wouldn't，就给点例句啦：Please don't talk so loud in the library.
I wouldn't drink wine before 18.

老师说的句子开头的not要变成don't或者wouldn't，意思有可能：
Not talk so loud（错误）所以要变为Don't talk so loud.
Not go anywhere（错误）所以变为Don't go anywhere.
在词组中用not的情况：
I am not going to play computer until six o'clock.
She should not (shouldn't) ate her brother's dinner.