你可以去把信拿来吗？can u go bring me the mail? 你可以去拿信吗？can u go get me the mail? 你带来了信吗？/你把信带来了吗？did u bring the mail with u? 我带来了信/我把信带来了 i've brought the mail with me.

In your question you don't need to add是。You just say "这些句子对不对？“ can you bring me the mail--- 你可不可以把邮件带过来。信 usually just refers to a single letter. can you go get me the mail? --- 你可以去拿邮件马？ Did you bring the mail--- 你有没有带邮件？ For the last one the correct would be 我带来了邮件。。。but orally you'd just say 我带了邮件。

1、 这些句子对不对， need not add “是" 2、 letter=信 mail=邮件/邮递 Your question: 1、 你可以去把邮件带来吗？ 2、 你可以去拿来邮件吗？ 3、 你带邮件了吗？ 4、 我带来了邮件/ 邮件我已经带来了

Note:（-）means delete the original character, while（吗） means increase the new Chineses character. Please see the sentence as below. 这些句子（-）对不对? 你可（-）以把信（件）拿来（吗）? – can you go bring me the mail 你可以（去）拿（-）信（件）吗? - can you go get me (bring?) the mail 你带来（-）信（件了）吗? – did you bring the mail with you? 我（的）信带来了 / 我带来了信 –I’ve bought the mail with me

你可（以）去把信（拿）来（吗）? – can you go bring me the mail 你可以去（拿）信吗? - can you go get me (bring?) the mail 你带来信（了）吗? – did you bring the mail with you? I’ve bought the mail with me 我带来了信。 或者 我的信带来了。