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a few hours ago和before的区别？
few hours ago和before的区别？
两个短语和单词都指的是之前的意思。
A few hours ago.通常只是用在过去时中。指的是几小时之前发生的事情，动词通常用过去式。 Before通常用在完成时中。动词要用它的过去分词加助动词的形式。
例如：
He was here a few hours ago.
I havent met him before.
a week before和a week ago的区别？
前者用在间接引语中 后者用在一般过去时的句子中
before ago yet late 的区别？
1、before在...之前，可以用于多种时态
Before I got home, he had already left.
You must get home before 5.
I havent been there before.
2、ago在...之前，常用于一般过去时
She arrived in China two days ago.
3、yet 尚未，还没有。常用语现在完成时
I havent read that book yet.
4、late 晚的,构成词组be late (for)
I was late for class this morning.
a week ago和before a week的区别？
没有before a week 的用法，只有a week before
a week ago的时间点是当前.
比如: I finished that work a week ago.(从现在算起)一周前我就完成了那个工作
a week before.后面要加时间点 可以加任何时间点
比如 :Ill leave to France a week before your birthday. 你生日的前一个星期我将去法国
ago表示“在此之前的几个时期”，意为“在今…之前”，需要与过去时或过去进行时连用。before泛指“在过去的几个时期之前”，意为“在过去的某个时候…之前”“与其…(毋宁)”，常和完成时连用，特别是在间接引语中，表示“在过去的一周之前”。
例如：
这封信是几天前寄来的。
The letter came a few days ago.
The letter came a few days before.
刚才她还在这儿。
She was herejust a minute ago.
She was here just a minute before.