from one side of something to the other

从一边到另一边:

the first flight across the Atlantic

跨大西洋的首次飞行

They ran straight across the road (=without stopping) .

他们径直跑过了马路。

We'll have to swim across.

我们只好游过去。

We'd got halfway across before Philip realized he'd left his money at home.

我们走到半路菲利普才意识到他把钱忘在家里了。

We gazed across the valley.

我们向山谷那边凝望。

towards someone or something on the other side of an area

朝，向〔对面〕:

There's Brendan. Why don't you go across and say hello?

那是布伦丹，你为什么不过去打个招呼呢？

The referee looked across at his linesman before awarding the penalty.

裁判先朝巡边员看了一眼，然后判点球。

He walked across to where I was sitting.

他走到我坐的地方。

used to say that something exists or reaches from one side of an area to the other

从一边延伸到另一边:

a deep crack across the ceiling

一道横穿天花板的深裂缝

the only bridge across the river

这条河上唯一的一座桥

Do you think this shirt is too tight across the shoulders?

你觉得这衬衫的肩部是不是太紧了？

Someone's parked right across the entrance to the driveway.

有人把车直当当地停在了车道的入口处。

on the opposite side of something

在…对面:

My best friend lives across the road.

我最好的朋友住在马路对面。

He knew that just across the border lay freedom.

他知道，越过边境就是自由。

Across the street from where we're standing, you can see the old churchyard.

在我们所站之处的街对面，你可以看到古老的教堂墓地。

the woman sitting across from me (=opposite me) on the train

火车上坐在我对面的女士

in every part of a country, organization etc

遍及，在…各处:

a TV series that became popular across five continents

在五大洲广受欢迎的电视系列片

Teachers are expected to teach a range of subjects right across the curriculum.

要求教师能够教授课程里的很多科目。

used to show how wide something is

宽:

The river is 2 km across.

这条河宽两公里。