Last night it was not known why the train came off the tracks.

昨晚火车脱轨的原因尚不清楚。

youdao

Why didn't you answer my Wechat phone at eight o'clock last night?

昨晚8点你为什么不接我的微信电话？

youdao

You may possibly wonder why all this was not told you last night.

你也许不明白为什么我昨天晚上不把这一切当面告诉你。

youdao

If the investigation was not compromised in any way by what came out last night, why didn't it come out a long time ago?

WHITEHOUSE: Press Briefing by Deputy Press Secretary Bill Burton

Martin Weale took the gloomier road in a speech last night, explaining why he thought interest rates should go up, even if the Bank is right in its current forecasts for inflation.

BBC: Inflation: Balancing the risks

Given eurozone ministers knew all this before they met last night you might wonder why they agreed to Bailout 2.

BBC: Eurozone deal: Greek default could still happen