empty 指空无一人或一物，或空洞无意义的。
vacant 普通用词，侧重某物或某个位置没有被占用。
hollow 指物体中间是空的。
blank 指上面没有写字、印刷或做记号的空白表面，或指上面留着准备被填写的空白处。
open 指未被占有，从而可被别人得到的。
参考例句
1. He opened the drawer and took out a cheque. 他拉开抽屉，取出了一张支票。
2. Sky is blue and mind is open. 天空是蔚蓝的，心胸是敞开的。
3. Dante: Sorry, not open for business yet. 但丁：对不起，还没有开始营业。
英英解释
n.
1. a clear or unobstructed space or expanse of land or water
2. where the air is unconfined
3. a tournament in which both professionals and amateurs may play
4. information that has become public v.
1. cause to open or to become open
2. start to operate or function or cause to start operating or functioning
3. become open
4. begin or set in action, of meetings, speeches, recitals, etc.
5. spread out or open from a closed or folded state
6. make available
7. become available
8. have an opening or passage or outlet
9. make the opening move
10. afford access to
11. display the contents of a file or start an application as on a computer adj.
1. affording unobstructed entrance and exit; not shut or closed
2. affording free passage or access
3. with no protection or shield
4. open to or in view of all
5. used of mouth or eyes
6. not having been filled
7. accessible to all
8. not defended or capable of being defended
9. (of textures) full of small openings or gaps
10. having no protecting cover or enclosure
11. (set theory) of an interval that contains neither of its endpoints
12. not brought to a conclusion; subject to further thought
13. not sealed or having been unsealed
14. without undue constriction as from e.g. tenseness or inhibition
15. ready or willing to receive favorably
16. open and observable; not secret or hidden
17. not requiring union membership
18. possibly accepting or permitting
19. affording free passage or view
20. openly straightforward and direct without reserve or secretiveness
21. ready for business
