of

英 [ɒv; (ə)v] 美 [əv]

1. 属格；限定，用of右边的内容去限定of左边的事物。
2. of就起一个限定作用。
3. 后接of与不接of的区别就在于是否需要进一步限定前面的事物。

of 的，在，当

来自古英语of,来自Proto-Germanic*af,来自PIE*apo,离开，词源同前缀ab-,apo-,apogee.后作用连词使用，其原词义见off.

of: of: [OE] Of has an ancient ancestry, going back to the prehistoric Indo-European preposition of ‘removal’ or ‘origin’, *ap. Its Germanic descendant was *ab, source of modern German ab (now only an adverb, meaning ‘away’), Dutch af, Swedish av, and English of. Latin ab ‘from’ (as in English abduct, abject, etc) also came from Indo-European *ap.
=> off
of (prep.): Old English of, unstressed form of æf (prep., adv.) "away, away from," from Proto-Germanic *af (cognates: Old Norse af, Old Frisian af, of "of," Dutch af "off, down," German ab "off, from, down"), from PIE *apo- "off, away" (see apo-). Primary sense in Old English still was "away," but shifted in Middle English with use of the word to translate Latin de, ex, and especially Old French de, which had come to be the substitute for the genitive case. "Of shares with another word of the same length, as, the evil glory of being accessory to more crimes against grammar than any other." [Fowler]

Also from 1837 a non-standard or dialectal representation of have as pronounced in unstressed positions (could of, must of, etc.)

1. No matter where you go in life or how old you get, there's always something new to learn about. After all, life is full of surprises.: 不管你生活在哪里，你有多少岁，总有新东西要学习，毕竟，生活总是充满惊喜。

3. Instead of complaining about what's wrong, be grateful for what's right.: 别抱怨不好的事，要对好的事心存感恩。

4. When life gets hard and you want to give up, remember that life is full of ups and downs, and without the downs, the ups would mean nothing.: 当生活很艰难，你想要放弃的时候，请记住，生活充满了起起落落，如果没有低谷，那站在高处也失去了意义。

5. The happiest are not those who own all the best things, but those who can appreciate the beauty of life.: 最幸福的人们并不一定什么都是最好，只是他们懂得欣赏生活的美好。