a是个词根，有三种意思：
1. 以某种状态或方式，如: ablaze, afire, aflame, alight, aloud, alive, afloat等
2. at, in, on, to sth，如: abed, aboard, abroad, ahead, afoot, ashore等
3. not/without, 如: amoral, asexual, atypical等

船的甲板和车厢的地板是板(board)，所以aboard是上板(车、船)。board可做动词，登机口的工作人员会喊boarding, boarding. 到广阔(broad)的地方去是出国(abroad).

说不正经的：Three days ago: 三天走掉了；away: 到路上去；She is abreast. (without sth)；Abreastalley (to sth) 听起来挺洋气的。Westminster Abbey. minster - a large or important church; aha!

说正经的：

1. The couple were both quite fat and were walking abreast (side by side) and blocked the whole path.
2. You can see them walking two abreast and you have to walk into the road to get past.
3. Some people walk three abreast and really slowly, forcing me to lower my pace until I spot a chance to get around them.
4. They are walking four abreast, so that they take up all of the narrow pavement (人行道).
5. They often, too, ride five abreast, causing car drivers to swerve (突然转向) to the other side of the road to pass them.
6. The police car got abreast of him and forced him to the curb (马路牙子).
7. It's a narrow corridor (走廊) allowing only two people to walk abreast.
8. The cars are parked closing head-on (头朝前) in line abreast.
9 .As those of us who have kept abreast of current events know, this is a profoundly important election.
10. I read the paper and a variety of magazines regularly, and likes to keep abreast of current affairs.
11. I read professional periodicals and keep abreast of the latest advances in the field.
12. By keeping abreast of all cutting-edge innovations, we are forearmed to react quickly to our client's changing demands.
13. They are working shoulder to shoulder with local residents.

abase abuzz across adrift afar afresh agape aglow aground ahead alike aloft amass amend amid amidst amiss amount anew apace apart apathetic apolitical arise around ashamed ashore aside askew asleep astern astride astringent asunder asymmetric asymmetrical asymmetry atheist (theology: 神学) atone atop avoid avow await awake awaken away aweigh