英语关于be动词和助动词的一点区别 请教一下啊

Question

我目前在自学语法 关于be动词和助动词do 的用法总混淆 比如 这一题
I wrote six letters yesterday
标准答案是 who did ou write to 我写成了 who were you writeing to 。。。
还有一题 Sarah (isn.t doing) her shopping during the week. she always does it
标准答案是 Sarah doesn.t do her shopping during the week. she always does it
请各位答疑一下，以及比较好的辨别 用be还是do 的方法，谢谢大家了

Answer 1

be doing 是正在做的事情才用的啊，就是进行时。
who did you write to 就是你给谁写信，信应该已经写完了。而who were you writing to （一般是who are you writing to?你正在给谁写信）就是过去进行时了，比如有人问你昨天晚上8点正在给谁写信可能会这么问。
所以do 就一个比较一般的状态，表示经常做或者一个陈述的状态。而be doing 就表示正在做了。像Sarah ( ) her shopping during the week. 很明显是说她这个星期没出去逛街，就是一个陈述或一般性的动作了，一个人总不会逛一个星期的街吧。所以你写成isn't doing 就犯了这样的错了。
再给你举个例子吧：你今天去哪儿了，Where did you go today；你去哪儿,Where are you going?
我觉得你就是搞不清进行时和一般现在时，不懂可以追问。

Answer 2

如果原来句子中有am is are ,was were 就直接用。如果句子中没有Be 就要用助动词do does did.
如he is a worker.--Is he a worker? What is he?
如He works in that factory. Does he work in that factory? Where does he work?
He went shopping yesterday. Did he go shopping yesterday? When did he go shopping?本回答被网友采纳

Answer 3

第一题：我昨天写了六封信，然后下一句要问的是，这些信你是写给谁地的？
而were+doing 是过去进行时。表示的是你昨天正在给谁写信。从意义上来说，就前言不搭后语。所以应该用一帮过去式，问你昨天都给谁写了信。才对符合逻辑。总而言之，这个题是一个考察时态的题。你还是没有把一般过去时态和过去进行时态区分开来。