In many words, IN- means the opposite or “not”:
在很多单词里，IN-前缀都是相反的或“不”的意思：
inconsistent = NOT consistent 不一致的
insufficient = NOT sufficient 不足的
independent = NOT dependent 独立的，不依赖的
incorrect = NOT correct 错误的，不正确的
However, there are some exceptions that might be confusing
但其实并不是所有的词都是这样，也是有例外的
If something is valuable, it means it is worth a lot of money, or is very important. A gold necklace is valuable – it might cost $1,000.
如果某物是valuable，意思是它值很多钱，或者非常重要。一条金项链很值钱——可能要1000美元。
You might imagine that invaluable means “not valuable” – but that’s not true! The word invaluable means extremely valuable; the value is so great that it is impossible to measure. A unique and famous painting like the Mona Lisa is invaluable.
你可能自然而然地就认为invaluable的意思是没有价值，但事实并非如此!Invaluable的意思是极其贵重的;它的价值是如此之大，以致于无法衡量。像《蒙娜丽莎》这样独一无二，举世无双的画作是无价的。
You can also describe non-physical things as invaluable – for example, if someone gave you advice that drastically changed your life for the better, you could say that their advice was invaluable – it was SO valuable and SO important that it’s impossible to measure how much it was worth.
你也可以把非物质的东西描述为无价之宝，例如，如果有人给你的建议彻底改变了你的生活，你可以说他们的建议是无价之宝——它是如此贵重并且重要以至于无法去衡量它的价值。
valuable / væljʊb(ə)l/ adj. 贵重的;有价值的;可估价的
invaluable /ɪn væljʊ(ə)b(ə)l/ adj. 无法估计的, 非常宝贵的
The adjective famous describes someone or something that a lot of people know about.
形容词famous描述的是很多人都知道的人或事。
Does infamous mean the opposite, “not famous”? No! Infamous means being famous for a BAD reason. For example, a criminal who has robbed 10 big banks would be an infamous bank robber – a lot of people know about him, but it’s because of something negative, because of his bad behavior.
那infamous就是它的反义词“不出名”的意思吗?不是!Infamous的意思是因为不好的原因而出名。例如，一个抢劫了10家大银行的罪犯会是一个臭名昭著的银行抢劫犯——很多人都知道他，但这是因为一些负面的东西，因为他的坏行为。
A person is infamous when they have a very bad reputation that is known by a lot of people. We can also use this word for things that are not people.
当一个人有很多人都知道的坏名声时，他就是臭名昭著的。我们也可以用这个词来形容非人类的事物。
If there’s a city that has terrible traffic all the time, we can talk about the infamous traffic jams there – again, well-known for a bad reason.
如果有一个城市的交通一直很糟糕，我们可以说那里有臭名昭著的交通状况，由于众所周知的一个坏事情而被周知。
famous / feɪməs/ adj. 著名的;[口]极好的，非常令人满意的
infamous / ɪnfəməs/ adj. 无耻的;声名狼藉的;邪恶的;不名誉的
Note that there’s a pronunciation difference as well:
注意一下这两个词发音上的不同：
FA-mous (“a” like in “name”, stress on “FA”)
a像是name里a的发音，重音在fa
IN-fa-mous (“a” sounds like “uh”, stress on “IN”)
a像是uh的发音，比较轻，重音在in
