Unit 1 Festivals around the World（Grammar and Useful Structures）
he may be very busy now. (可能性較大)
he might be very busy now. (可能性較小)
2） 表示許可（permission），表示允許別人做某事， 也可征求對方的許可。
he may go now.
we may keep the book for two weeks.
3) 用于祈使句，表示祝愿。
may you succeed!
may you have a nice trip!
3. will and would
1）表示意愿
表示愿意做或主動提出做，如意志，愿望或決心等，例如：
that bag looks heavy, i’ll help you with it.( offering to do sth)
---- you know that book i lent you. can i have it back if you’ve finished with it?
---- of course.. i’ll give it to you this afternoon.(agreement)
thanks for lending me the money, i’ll pay you back on friday. (promise)
2） 表示習慣(habit, custom)
this old man is strange. he will sit for hours without saying anything.
we would sit around grandpa after supper, listening to his stories.
3）表示請求（request）， 用于第二人稱， would 比will 更委婉。 例如：
will you come this way, please?
would you open the window?
4. shall and should
1）shall 的用法
a. shall 在疑問句中用于第一，第三人稱，表示征求對方的意見。
shall we put off the sports meeting until next month?
shall tom go there with me tomorrow?
b. shall 用于第二，第三人稱，表示說話人給對方的命令，警告，允諾或威脅。
you shall fail if you don’t work harder. （警告）
he shall have the book when i finish reading it.(允諾)
he shall be punished.(威脅)
2) should 的用法
a. should 表示勸告、建議、命令。
you should go to class right away.
b. should 表示期待，用于表達合理推斷（prediction，意為“應該” ），或明顯的結果（意為“可能”）且所期待的事幾乎是事實。
it is three o’clock, the football game should begin now.
mary took dancing lessons for years, she should be an excellent dancer.
5. must 與 can’t
must 用來表示“命令”、“推測”等含義。
1）表示規定、指令
表示規定、指令時主要指客觀上的法律、條文規定，常常翻譯為“應該、必須”之類意思。mustn’t 表示禁止
you must have a passport if you want to go abroad.
drivers mustn’t drive after drinking.
2) 表示主觀的命令、禁止
表示主觀的命令、禁止時，主要指說話者主觀的命令或強烈的勸告。
you can go out with your friend but you must come back before 11 at night.
----must i hand in the exercise today?
----no, you needn’t.
3）表示猜測，語氣非�？隙ǎ醮_定的意味，一般用于肯定句，意為肯定……。其否定為can’t，意為不可能…...
you must be ill. i can see it from your face.
he can’t be at home. i saw him in the classroom just now.
step 4 summing up
from the demonstration of the modal verbs above, we can find most of them can be used to express certainty, but the degree of them is different.