一旦
Used to indicate that something has only been true since the occurrence of something else.
用来表示在某物出现之后才发生的情况。
I only started to seriously rethink my life once I graduated college.
大学毕业之后，我才开始认真反思自己的生活。
Once I actually started going to museums, I realized that I really liked them.
当我真的去过图书馆，我意识到我很喜欢它们。
I don’t know how Jared is so charismatic. Once he starts a trend, everyone else quickly follows.
我不知道为什么杰瑞德这么有魅力，一旦他开始做某件事，其他人就会跟随他。
9.IF
如果
Can be used to set up a condition in a hypothetical situation.
可以用在假设情况下设置条件。
I’ll scratch your back if you scratch mine.
如果你抓我的背，我就会抓你的背。
If something’s bothering you, don’t hesitate to tell me.
如果有什么事情让你感到烦恼，你尽管告诉我。
The conjunction “if” can be emphasized with the word “even.”
连词“if”也可以用“even”来强调。
I wouldn’t tell you his secret even if you begged me.
即使你求我，我也不会把他的秘密告诉你。
Even if I’m having a bad day, I try to be nice to people.
即使这一天我过得并不好，我也尝试着对其他人好一点。
10.AS IF
好像
Can be used to mean something like “pretending that something were true”
可以用来表示“假装某事是真的”
He treats me as if I were his sister, not his girlfriend.
他对我就像对姐姐一样，而不是像对待他的女朋友。
Don’t try to lecture me as if you actually knew what you were talking about.
不要试图说教我，就好像你知道你在说什么一样。
You tend to brush most things off as if they’re no big deal.
你什么都不在乎，就好像他们不是大事儿一样。
11.LIKE
像…一样
Can be used as an alternative to “just as.” Can be emphasized by the word “just.”
可以用作“just as”的替代品。也可以用“just”来强调这个词。
I did the dishes like you told me to.
我按照你告诉我的方法做了菜。
The dish that was served looked just like it did in the menu.
这道菜看起来和菜单上一样。
Can also be used as an informal alternative to “as if”
可以用作“as if”的非正式替代词
Sometimes I feel like Keira ignores me on purpose.
有时候我觉得凯拉故意不搭理我。
Don’t treat me like I’m an idiot.
不要这样对我，好像我是个傻子一样。
12.UNLESS
除非
Can be used to introduce an exception to a statement
可以用来说明一种陈述的例外
The professor said not to email her unless you have a logistical question.
教授说除非有逻辑上的问题，否则不要给他发邮件。
I personally won’t date you unless I find you attractive.
除非我觉得你很有吸引力，否则我不会跟你约会。
The visiting team is going to win unless the tables somehow turn last minute.
除非在最后一刻有转机，否则客队就要赢了。
13.IN CASE
万一
Can be used to mean something like “for the possibility that something might happen”
可以用来说明某事有发生的可能性。
I sent the message twice in case the first one didn’t go through.
怕第一个短信没有发出去，我发了两次短信。
Can you double check the document just in case there aren’t any errors?
以防有错误，你能不能再检查一下。
14.WHETHER
是否，不论
A shortened form of “whether or not”
是“whether or not”的缩写形式
I’m not sure whether we’ll be able to hit everything on the itinerary.
我不确定我们是否能够按行程完成所有的事。
Can you tell whether this was handwritten?
你能告诉我这是否是手写的？
Do you care whether I’m in the room while you’re on the phone?
你打电话的时候介意我在房间里嘛？
15.ALTHOUGH
虽然，尽管
Can be used to mean “despite the fact that” or “regardless of the fact that”
可以用来表示“不管事实怎样”或者“尽管事实怎样”
Although he was a bit rude, people still found him funny and hung out with him.
尽管他有一点粗鲁，但是人们还是觉得和他在一起很有趣。
Although the party was dull, I was still happy to see you guys.
虽然聚会很无聊，但是我还是很高兴见到你们。
本文来自：逍遥右脑记忆 http://www.jiyifa.net/chuzhong/1177927.html
相关阅读：这脑洞给赞！墨西哥警察局给警员配备弹弓