A backpack sends O2 in to let astronauts breathe normally.

一个背包可以输送氧气，让宇航员正常呼吸。

youdao

A large tree might make around 100kg of O2 per year.

一棵大树每年可以产生大约100公斤的氧气。

youdao

It takes about 7 to 8 trees to make enough O2 for one person to breathe for a year.

大约需要7到8棵树产生足够一个人呼吸一年的氧气。

youdao

Michael Jackson's 50-night run at London's O2 arena was to have set a new course for the entertainer.

VOA: standard.2009.06.26

And what I want to point out that we just figured out for molecular orbital theory, is that o 2 is a biradical, because remember, the definition of a radical is when we have an unpaired electron.

我要指出的是,我们刚利用分子轨道理论，指导了O2是二价自由基，因为记住，自由基的定义是,有个未配对的电子。

麻省理工公开课 - 化学原理课程节选

We put the magnesium 2 plus here, and then we put the oxygen here, O 2 minus, and we know that this gives us our R zero, right?

我们把Mg2+放这，然后O2-放这，我们都知道这给我们的是R0，对么？

麻省理工公开课 - 固态化学导论课程节选

This resulted in the band reforming for the concert at London's O2 arena in December 2007.

WSJ: 'Imaginative' Oxford Gift to Boost Humanities Study

He first performed at the festival in 2007, shortly before his 21-night residency at London's O2.

BBC: Prince to headline Montreux Jazz Festival

It will extend the O2 phone number and package far beyond just the mobile handset.

ENGADGET: O2's TU Go software spreads your phone number across multiple devices