外研版高中英語必修三《The world of science》PartⅡ PPT課件，共19頁。
《The world of science》PartⅡ PPT課件包括語法精講、即學即練等內容。
一、基本特征感悟
①Over time I have been changed quite a lot.
②Since the 1970s many new applications have been found for me.
③The important problem has been discussed for nearly two weeks.
④The ink has not been removed from the clothes.
⑤Haven’t your problems been solved?
⑥How many buildings have been built in your school?
二、主要用法精講
1.結構
Already this year，115 measles cases have been reported in the USA，compared with 189 for all of last year.
今年美國已經報告了115例麻疹病例，而去年全年共189例。
The construction of the bridge has not been finished.橋的建設還沒有完成。
Has the date for the next meeting been decided？下次會議的日期已決定了嗎？
How long has the battery not been changed？電池多久沒有更換了？
2.用法
(1)現在完成時的被動語態同它的主動語態一樣，強調過去的動作對現在造成的影響或結果，通常與already，yet，just，never，recently等副詞連用。
The machine has already been repaired.機器已經修好了。
(2)表示一個被動的動作或狀態開始于過去，持續到現在，并可能持續下去，常與for或since引導的時間狀語連用，或用于“How long...？”句型中。
Financial problems of the company have been discussed for nearly two hours.
公司的財務問題已被討論了近兩個小時了。
How long has this film been shown？這部電影已放映多長時間了？
3.注意事項
... ... ...
關鍵詞：The world of science PPT課件免費下載，.PPT格式；
