表示原因as / because /since / now that
as 因为、由于
As it was getting late , we decided to book into a hotel.
因为天色已晚，我们决定投宿一间旅馆。
You can go first as you're the oldest.
你可以第一个去，因为你年纪最长。
because 因为
I can't go to Amy's party because I am going away that weekend.
我不能参加Amy的聚会，因为我那个周末会不在。
Because there was a long queue in the duty-free shop, Jenny almost missed her flight.
因为免税店排队排得很长，Jenny几乎错过她的班机。
since 因为、既然
Since we've got a few minutes to wait for the flight, let's have a cup of coffee.
既然还需要几分钟等班机，咱们去喝杯咖啡吧。
Joey must have taken the book since it isn't here.
Joey一定已把书拿走了，因为书已不在这里了。
now that 既然，由于
Now that you are here, you may as well stay for a few days.
既然你来了, 就不妨住几天吧。
Meg is enjoying the job now that she's got more responsibility.
Meg因为承担了更多的职责，所以很喜欢这份工作。
表示条件if / unless / whether or not /even if / in case
if 假如，如果
We'll have the party in the yard if the weather is good.
如果天气好的话，我们将在庭院里开派对。
If you invite them, they will come.
如果你邀请他们的话，他们会来。
unless 除非
You can't travel abroad unless you have a passport.
你无法出国除非你有护照
I will go swimming tomorrow unless it's cold.
我明天会去游泳除非天气冷
whether or not 是否、不管、无论
Please tell me whether or not you're interested.
请告诉我你是否有兴趣
Whether or not it rains, we are going hiking on Sunday.
无论是否下雨，我们星期日都要去爬山。
even if 即使
Even if you take a taxi, you'll still miss your flight.
即使你搭计程车，你还是会赶不上班机。
You have to hand in your examination paper even if you are not finished.
即使你没写完，你也必须要交出考卷。
in case 以防万一、不时之需
Matt, bring a map in case you get lost.
Matt, 带张地图吧，以防迷路了。
In case you need to reach me, I will be at my parents' house.
以防你需要找到我的话，我将会在我父母的家。
表示对比although /though / even though
although 虽然、尽管
Although I had all the necessary qualifications, I didn't get the job.
虽然我具备了所有的条件，我并没有得到那份工作。
Maggie is not satisfied although she has everything she wants.
虽然要什么有什么，Maggie还是不满足。
even though 虽然、尽管
Susan didn't learn Japanese even though she lived in Japan for a year.
虽然住过日本一年，Susan 并没有学日文。
Even though Gary doesn't get much exercise, he is in good shape physically.
尽管Gary没做太多运动，他的身材保持得很好。
though 虽然、尽管
I went swimming though the weather was cold.
虽然天气冷，我还是去游泳。
Though Sally was hungry, he didn't eat anything.
虽然Sally很饿，她什么东西都没吃。
