中文的可能，確信程度沒有分高低。但是英文的可能卻有程度之分。一起和Crown Academy of English 的講師 Andrew學習Must, have, could的用法吧!
主詞 + must + 原型動詞
You must be tried!
He could be in the garden.
They can’t have much money.
Jane 正在和Sarah講電話，並給她一些建議。我們只能聽到Jane說什麼。從Jane 說的話裡我們可以猜猜Sarah怎麼了。
Sarah, listen to me. You have to try to forget about this man. You live in Manchester and he lives in London. It’s too far and your lives are different.
Stop listening to his songs because that will make you sad.
You must try to make some friends.
You have a difficult job working at the hospital, so try to rest on the train before work.
For the pain, take an aspirin.
What do we know about Sarah?
1.Sarah must be in love with a singer.
從Stop listening to his songs because that will make you sad.和try to forget about this man判斷Sarah一定在和一個歌手談戀愛
2.Sarah could be a doctor or nurse.
You have a difficult job working at the hospital，我們知道她在醫院工作，但無法確定她是醫生還是護士。所以用could應該
3.She might have a headache.
For the pain, take an aspirin. Jane建議Sarah吃止痛藥，我們猜測Sarah可能有頭痛，但是不確定是頭痛還是其他地方不舒服。
4.Sarah can’t have many friends.
You must try to make some friends.從此據判斷，我們很清楚知道她沒有朋友，所以直接用否定can’t。
5.She might not have a car.
try to rest on the train before work. 說道她搭火車去上學，她可能有車也可能沒有車