現(xiàn)在完成時(The Present Perfect Tense)
1. 動作發(fā)生于一個非確定的過去的時間(過去的時間并不重要或根本不知道),但它的結(jié)果仍對現(xiàn)在有影響.
I have read the letter, and I know what it is about.
2. 動作發(fā)生在過去,目前仍在繼續(xù)或剛剛結(jié)束, 常和 "for" 加上 "一段時間", 或"since" 加上"一個確切的過去的時間" 連用.
a) "for" 用于過去的一段時間. (動詞必須是可以延續(xù)的)
He has been there for six months. 她去那兒有6個月了.
(直到現(xiàn)在)
He went there 6 months ago.
He has never been there. 他從來都沒去過那里.(直到現(xiàn)在)
b) "since" 用于過去的一個確切的時間, 意思是"從那時一直到現(xiàn)在", 總是和完成時一齊用, 而且不能省略. (主句動詞必須是可以延續(xù)的)
Tim has been in Nantong since January. 自從1月份以來他一直都在南通.(現(xiàn)在仍在南通)
注意: "since" 后面的確切的過去的時間也可以是一個含有過去時的從句.
He has been interested in collecting coins since he was a child.
他打小時侯起就對收集硬幣感興趣.（現(xiàn)在還是如此）
c) 現(xiàn)在完成時常和短語 "up to now /till now", "so far" (意思是從過去某一確定的時間一直延續(xù)到現(xiàn)在.)
Up to/till now he's read many story books. 至今他已讀過好多故事書.
I've been to New York three times so far. 至今我已到紐約去過三次.
3. 剛剛完成的動作.
I've just got a letter from my brother.
4. "already" 用于現(xiàn)在完成時的肯定句中, "yet" 用于現(xiàn)在完成時的否定句和疑問句中
He has (already) visited many places in China. (already)
He has come back now. Have you ever been to Australia?
注意 "already" 在句中的兩種位置.
The train hasn't arrived yet.火車（到現(xiàn)在）還沒有到.
Has she arrived yet? 她已經(jīng)到了嗎?Hasn't he come yet? 她還沒來嗎?
I haven't been very successful so far.我一直都沒有成功.
注意: "have been"（去過） 和 "have gone"（去了） 的區(qū)別:
He has gone to Beijing . (He is there or is on his way there.)
He has been to Shanghai . (He was there once, but he is not there now.)
5. 當現(xiàn)在完成時句中無時間狀語, 它只是指一個簡單的已經(jīng)完成的動作
I've cleaned the sitting-room. 我已把起居室打掃過了.(已完成了工作)
6. 現(xiàn)在完成時可以用來表示一個反復(fù)發(fā)生的動作.
He has rung me up five times today. (五次分隔的行為)