两个都不跟从句。
I usually go on holiday by air.
我经常坐飞机去度假。
As time went by， he came to know the importance of friendship.
随着时间流逝，他逐渐知道友情的重要性。
They wouldn't let us through.
他们没让我们过去。
I'll take a through train.
我想搭直达车。
We all got through our examinations.
我们考试都通过了。
We are through school at five o'clock.
我们五点上完了课。
They became unemployed through no fault of their own.
他们的失业不是由于自身的过失造成的。
through和by，哪个后面可以跟句子
by 和 through 都可以作为介词，有相近的意思，它们的主要区别是 by 用来提及某事的方式方法，而 through 是用于任何过程的介词。
一、by 表示靠近或经过某物，与物体之间是有距离的而 through 表示从一个地方到另一个地方或穿过一个地点，通常是从地方或地点中间穿过，例如：
by：
Our grand parents’ house is situated by a beautiful river.
我们祖父母的房子坐落在一条美丽的河边。
through：
You have to go through the forest to get to the village.
你必须穿过森林才能到达村庄。
二、by 用来提及某事的方法，方式或手段，而 through 用来提及过程，流程或步骤等，例如：
by：
For the transaction I wish to pay by cash.
我想用现金支付这笔交易。
through：
You can only achieve success through hard work.
你得孜孜不倦方能成功。
