PREMISSION：OTHER TENSES 在其他時態中表示許可
表示許可的can在過去時里可用could:
We could use his pool whenever we wanted to.我們隨時都可以用他的游泳池。
而在條件時態里，也可以使用could:
If we were in the USA, I could drive a car at 16.如果我們在美國，16歲我就可以開車。
這時也可以用allow或permit來代替could..例如， 上面過去時態的例子變成下面這樣：
We were allowed to use his pool whenever we wanted to.
而上面條件時態的例子可以這么用：
If we were in the USA, I would be permitted to drive a car at 16.
If we were in the USA, they could permit me to drive a car at 16.
其他時態都只能用allow和permit:
Has he ever been allowed to use this phone?他被允許用這部電話嗎？
I had never been permitted to go into his room before that day.在那天以前從來不讓我進他的屋子。
Will she be allowed to come to the party?她會被允許參加聚會嗎？
USING ‘CAN’ TO EXPRESS ABILITY 用can表示能力
情態動詞can還可以用來表示能力，can只能用在現在時里：
Woman Can you play the piano and the guitar?你會彈鋼琴和吉他嗎？
Man I can play the piano, but I can’t play the guitar.我會彈鋼琴，但我不會彈吉他。
過去時態里要用could:
I could read when I was four.我4歲的時候就會閱讀了。
I couldn’t swim until I was 15.直到位5歲我才會游泳。
而在條件時態里，要用could這種時態：
If you learne french, you could help me.如果你學了法語，你就可以幫我了。
還可以用be able to來代替上述can和could.例如上面研修例子可以改寫成下面這樣：
I was able to read when I was four.
I wasn’t able to swim until I was 15.
If you learned French, you would be able to help me.其他時態都必須用be able to :
I have been able to speak Swedish for many years.我會說瑞典語很多年了。
I would love to be able to play a musical instrument.我很希望能演奏某種樂器。
USING ‘CAN’ TO EXPRESS POSSIBILITY 用can表示可能性
can還可能用來表示可能，它表示的是一般的可能性性：
In winter, you can ski there.冬天，你可以在那兒滑雪。
You can drive there in less than an hour.開車不到位個你就可以到那兒。
有時屆用來表示會發生的可能：The tide here can be dangerous.這兒的湖水很危險。
Mosquitoes can be a problem near the lake.待在湖的附近，蚊子是個問題。
在過去時態里要用could:
We used to live in Canada. In winter, you could ski there. In summer, mosquitoes could be a problem.
MULTI-WORD VERBS:WITH ‘UNDER’ under的短語動詞
under的基本意思是“在……之下”， 它可以和許多動詞一起使用，但慣用句卻并不多。
首先，看一下使用字面意思的under詞組：
The fox crawled under the fence and escaped.狐貍從籬笆下爬出去逃跑了。
Get under the blanket to keep warm.蓋上毯子會暖和點兒。
The sailors tried hard, but eventually the boat went under.船員們努力營救，最終還是沉了。接下來的是under和動詞組合后，產生的許多新的意思。
