短语讲解：

1. Once users were able to access Twitter again, many posted about what they did during the Twitter outage, instead of writing tweets or checking for updates.

be able to 能够做; 能,会
例句：We study samples in order to be able to describe populations.
为了了解总体，必须研究样本。
instead of （用…） 代替…， （是…）而不是…， （用…）而不用…
例句：I decided to treat myself to a taxi, eg instead of walking.
我决定坐他一次计程车。