英语翻译1因为那时她在外地出差,所以她没来我翻译成：she isn't came back,because she go

第一句翻译 “那时”表明是过去时态 所以整句都要用过去式
首先 isn't came 这是很明显的语法错误 两个动词怎么可以这样放在一起,不说时态, she go 也是语法错误,she是三单,动词go要用三单形式 come back是回来和来 是有区别的 所以用come就可以了
第一句的翻译：She didn't come because she went on business at that time
第二句翻译 相对而言简单,时态上,我也觉得用过去时态更好,因为题目是看见,既然是看见,就是已经发生了,用过去时态
第二句的翻译：I heard her laugh/laughter.
第三句,时态上,我还是觉得用过去时态更好,当然这句的话用现在完成时态也可以
你的翻译有两大错误,第一注意 这个词的话,我觉得用notice更好,attention是名词不可以当动词这样用.还有him left 也是不对的,left是动词不可以在名词后面再出现.你要记住两个动词之间一定要有连词,不能同时放在一起.
第三局翻译：Nobody noticed his leaving.或者 Novody has noticed his leaving.

1因为那时她在外地出差，所以她没来：She didn't come, because she was away on a business trip at that time.
2我听见她的笑声: I heard her laugh/laughter.
3没有人注意他离开：Nobady noticed his leaving/depart.

She didn't come back,because she was on a business trip then.
I heard her laughter.
Nobody noticed his leaving.
第二句和第三句的失态也可以用一般现在时。