She has returned from Paris.

她已从巴黎回来了。

She returned yesterday

她是昨天回来了。

He has been in the League for three years.

(在团内的状态可延续)

He has been a League member for three years.

(是团员的状态可持续)

He joined the League three years ago.

( 三年前入团，joined为短暂行为。)

I have finished my homework now.

---Will somebody go and get Dr. White?

---He’s already been sent for.

句子中如有过去时的时间副词(如 yesterday, last, week, in 1960)时，不能使用现在完成时，要用过去时。

(错)Tom has written a letter to his parents last night.

(对)Tom wrote a letter to his parents last night.