Unit 1 Festivals around the world
eg.his mother wasn’t at home, so he was able to watch tv
2) may and might
may we see the awards for teams?(permission,request)
she might give yousome new clothing.(possibility)
注意：1.表示許可時，用于第一人稱，指我（們）被允許做某事；由于其他人稱，則指說話者允許主語做某事。
eg.we might go shopping until dark.(我們被允許)
mother said:”you might go shopping until dark.” （說話者允許主語做某事）
2.在用于請求許可時，may可與can/could 互換
3）will and would
the spring festival is the most fun. the whole family will come for dinner.(promise;agreement)
often he would dress up like a rich man.(past habit; custom)
would you like to join us for dinner?(request)
注意：would 與 used to 均可表示“過去慣常”，但是would 常與過去時間狀語連用，意為總是，總要；used to 與現在時間相比，意為過去常常，暗示現在已經沒有了。
eg.when he was there, he would go to that coffee shop at the corner after work every day?
he used to go to that coffee shop at the corner after work every day,but now he goes to play basketball.
4)shall and should
the harvest festival begins on saturday.we shall be there with our friends.(promise, agreement)
it’s nearly five o’clock. the taxi should be here soon.(prodiction)
注意：1.shall 用于第一，三人稱的疑問句中，表示說或者征求對方的意見，或向對方請示。
eg.shall we go shopping after school?
2.should have done 表示過去應該做而沒有做
should not have done 表示過去不用做而卻做了
5）must and can’t
wang feng wins an award every year. he must be very strong.(speculation)
you must be joking. that can’t be true. (guessing)
對現在的事情進行把握較大的判斷時，肯定判斷用must+動詞原形，否定判斷用can’t+動詞原形。
she must be in the library.
she can’t be in the room.
2.modal verbs+ have done
一、情態動詞+動詞完成式
情態動詞+動詞完成式即“情態動詞+ have + done分詞”，表示對過去行為或動作進行推測、評論或判斷。
1. must have done表示對過去某事的肯定猜測。其否定或疑問形式都用can(could) 來表示.
since the road is wet, it must have rained last night.
he can’t have missed the way. i drew him a map.
“the dictionary has disappeared. who could have taken it?”
當然對現在發生或將來發生的事情,要用must do 表示猜測, 否定為can’t do.
he must understand that we mean business.
you must be hungry after a long walk.
2.may / might have done
may / might have done 表示推測過去某事“也許”發生了.may 比 might 表示的可能性在說話人看來稍大些。例如：
i can’t find my keys. i may / might have left them at the school yesterday.
3. could have done 在肯定句型中, 往往用作委婉的批評. 本應該做什么,而沒做; 有時也用作猜測.