1)用作动词动词：打开门，经营、开办
open a door/window/a small shop/one's hand/one's eyes/one's mouth/fire开门/开窗/开一家小商店/张开手/睁开眼/张开嘴/开火be opened to traffic通车open up开采（发）
Now，he opens a small factory of his own.现在他自己办了个厂。
Open the door， please!请开门！
2）用作形容词，表状态，"开着的"：keep open开着门be open开门、开业cut…open切开leave the door open 开着门in the open air 在野外an open secret公开的秘密keep one's eyes open睁眼
Don't keep the door open. 别让门开着（即：请把门关上）。
3) be open to对……开放
Many school libraries are open to children on Sundays.不少学校的图书馆周日给孩子们开放。
(2)（景色等的）展现
A beautiful view opened up before us.一幅美景展现在我们面前。
(3)开发，开辟，创建
open up a new situation / a bright future / more waste land开创一个新局面/美好的前程/开辟更多荒地
(4)吐露真情
She never opened up to me on the subject.关于那个问题，她从未对我开诚布公
