在看电脑用英语可以说是 "they are using the computer" 或者 "they are on the computer"。
来源：
"Using the computer" 是一个常用的表达，用来描述人们正在使用电脑进行某些活动。
"On the computer" 也是一个常用的表达，用来描述人们正在使用电脑进行某些活动。
下面是一些英文例句及其中文翻译：
They are using the computer to do their homework. (他们在用电脑做家庭作业。)
She is on the computer playing games. (她在电脑上玩游戏。)
He is using the computer to write a report. (他在用电脑写报告。)
They are on the computer browsing the internet. (他们在电脑上浏览网页。)