Unit3 The Computer and the Information Age-grammar教案
3》警示 進行時還常用在語境中，表示語氣的委婉。如： ---what are you going to do? ---i'm hoping to invite you to dinner. 5.完成時。 1》概念 本時態是表示某動作或某過程在一定時間內處于完成的狀態。 2》理解 完成時包括現在完成時和過去完成時態。構成分別為have<has> done/had done. <一>現在完成時。動作在過去發生，持續到現在已經完成，或者是繼續持續下去。 <1> 已經完成的用法。其表明某動作或過程發生在說話前某個不明確的過去時刻，到目前一完成，并對目前造成影響。如：he has not been to shanghai/have you finished reading the story ? 本用法常和不確定時間狀語連用。如：already/yet/before/recently/lately/just...等 i have seen him before we haven't been there lately 也可以和表示頻度的時間狀語用在一起。如：ever/never/once---等。 i have never been to hongkong. have you ever visited the great wall ? <2> 未完成的用法。本用法表示某動作或狀態開始于過去某個時刻一直延續到現在，而且還要繼續下去，在某種情況下也可能剛剛結束。常和 since/for/時間狀語連用。如： he has been in the army for 3 years. he has lived in the building since he came here. 3》警示：如果不過since 引導的從句中的動詞是延續性的，一般認為，語意上也表明動作或狀態的結束。如： i haven't heard from him since he lived there. 從他離開那兒以來，我一直未收到他的消息。 he has written to me frequently since i was ill. 從我病愈以來，他常給我寫信。 如果since引導的從句中的謂語動詞用了現在完成時，那么表示的動作或狀態就不表示完結。如： i haven't heard from him since he has lived there . 從我住在那里以來，我一直未收到他的來信。 he has written to me frequently since i have been ill. 從我生病以來，他常給我寫信。 <二>過去完成時。本時態表示的是動作在過去的過去發生。它也分為“已完成用法”和“未完成用法”。 1>已完成用法。表示，當一個動作發生或結束時，在它之前的另一動作已經完成。這種用法既用于動作動詞，也用于狀態動詞。如： when we arrived the cinema,the tickets have been sold out. tom flew home,but his father had already died.