by的核心含义是“依靠”。
by boat/bus/car/plane 乘（依靠）船/公共汽车/轿车/飞机；by air/land/sea 坐（依靠）飞机/经（依靠走）陆路/海路；travel by day/night （依靠）白天/夜间旅行
She could perfectly well manage by herself. 她完全能把事情处理好，依靠她自己。
The house is heated by gas. 这房子是用（依靠）煤气供暖的。
We had to work by candlelight. 我们不得不借助（依靠）烛光工作。
May I pay by cheque? 我能用（依靠）支票付款吗？
Switch it on by pressing this button. 启动它，（依靠）按下这个开关。
I took him by the hand. 我拉着他，依靠（拉）他的手。
Pick it up by the handle! 抓着（依靠）手柄把它提起来！
“依靠”可以引申为“以、按”。
We rented the car by the day. 我们租用汽车，以日租（的方式）。
They're paid by the hour. 他们被支付报酬，按小时（的方式）。
It was getting worse by the minute. 情况恶化，以分钟（的方式）。——情况急速恶化。
We only sell it by the metre. 我们只按米（的方式）卖。
The bullet missed him by two inches. 子弹没打着他，以（只差）两英寸距离（的方式）。
House prices went up by 10%. 房价涨了，以10%（的幅度）。
They met by chance. 他们相遇，以偶然（的方式）。——不期而遇
I did it by mistake. 我做了这事，以错误（的方式）。
I swear by Almighty God. 我发誓，以全能的上帝（的名义）。
She did not abide by the terms of the agreement. 她没有遵守，（按）协议条款（的要求）。
由“依靠”还可以引申为“从...（角度）看”。
By my watch it is two o'clock. 从我的表看，现在是两点钟。
He's German by birth. 他是德国人，从血统角度看。
They're both doctors by profession. 他们两人都是医生，从职业角度看。
I could tell by the look on her face that something terrible had happened. 我从她的脸色看出，发生了可怕的事情。
By law, you are a child until you are 18. 从法律规定看，你还是个孩子直到18岁（以前）。
“依靠”用于被动语态，可以表示“被”。
He was knocked down by a bus. 他被一辆公共汽车撞倒了。
Who's that book by? 谁是那本书的作者？（那本书是被谁写的？）
I was frightened by the noise. 我被那响声吓坏了。
6 multiplied by 2 equals 12. 6被2乘等于12。
“依靠”用于空间，表示“靠着、挨着”。
a house by the river 河边的一所房子（房子挨着河）
The telephone is by the window. 电话在窗户旁边。（挨着窗户）
Come and sit by me. 过来坐，挨着我。
He stood by her when while she telephoned. 他站在她身边（挨着她），在她打电话的时候。
由“靠着、挨着”引申为“（短暂）经过”。
He walked by me without speaking. 他一言不发地从我身边走过。
She also took my hand as we passed by the woods. 当我们走过树林时，她还牵着我的手。
They invited us to stop by the house for coffee. 他们邀请我们（稍做）停留，到家中喝杯咖啡。
由“经过”引申为“接着”。
They're improving day by day. 他们在一天天地改进。（一天接着一天）
We'll do it bit by bit. 我们会一点一点地做。（一点接着一点）
The children came in two by two. 孩子们一对一对地走了进来。（两个接着两个）
The room measures fifteen feet by twenty feet. 房间15英尺宽20英尺长。（15英尺接着20英尺）
空间上的“依靠”用于时间，可以表示“到…时（为止）”。
Can you finish the work by five o'clock? 你能完成工作吗，到五点钟（为止）？
We’ll all be dead by then. 我们将都已死去，到那时（为止）。
By this time next week we'll be in New York. 到下星期的这个时候，我们将在纽约。
By the time this letter reaches you I will have left the country. 到这封信到你（手里）的时候，我已离开这个国家了。
by的副词用法也可以表示“（短暂）经过”。
Just drive by. Don't stop. 直接开过去。别停车。
He hurried by without speaking to me. 他匆匆过去了，没和我说话就。
I'll come by this evening and pick up the books. 我今晚过来取书。
Time goes by so quickly. 时光飞逝。
I've put some money by for college fees. 我已经存了些钱作大学学费。（钱经过我这儿）
