复习英语语法-现在完成时

现在完成时

1.现在完成时：用来描述过去已有经验；

She has ('s) finished the game.（陈述）
Has she finished the game?（疑问）Yes, she have.
Has she ever finished the game?（疑问，常与ever搭配）
She has ('s) never played that game.(否定，不用not，常用never)

2.现在完成时用来描述过去发生且对现在还有影响。

I have had lunch.(I am not hungry now)
Your sister has arrived.(She is here now)

just、already、yet

A have just done sth. # 表示某人/某事刚刚发生；

She has just had lunch. # 她刚刚吃过午餐；

人/物/事+ have already + done # 表示某事刚刚发生；

She has already had lunch. # 她已经吃过午餐了；

yet只用于疑问和否定句；在否定句表示某事没按期待完成；在疑问句表示某事是否按预期做完了。
Have she had lunch yet?（她吃过午餐了吗？预期是她吃过了）
She hasn't had lunch yet? （她还没吃午餐）

for 和 since

This building has been built for three years. # 这栋楼已建好三年了
This building has built since 2016; # 表示从2016年开始（到现在）这栋楼就建好了，现在还在。
How long has the building built? # Since和for都使用how long来提问。

现在完成与过去式的比较

	现在完成	过去式
since	She has arrived NewYork since last month.[她上个月到纽约(现在还在那里)]	She arrived NewYork. [她去过纽约（现在不一定在那)]
this morning/day/week/month/year	Tom has caught a rat this morning.Tom 早上抓到一只老鼠(现在还是早上)	Tom caught a rat this morning. Tom 早上抓到一只老鼠(现在是下午或晚上)