我们不能英语

这句话使用can , could , need , should ， 语气都不强烈。楼主看过哈利波特5吗？里面的女BT强迫哈利波特在纸上写 "I must not lie ." 我不能撒谎 。这是最强烈的否定形式，比can要强，因此根据你的原意应该翻译为： We must not fight against each other .

we cannot judge by one's appearance

hey come on guy.. fuck u. why do u wanna fight with me.. just go out of me. don't bother me ,ok?

we can

We cannot fight.We cannot fight with each other.

You can't judge a book by its cover.

No we can't.