Makes sure that you say so, " cial, " social.

确保你说的是cial，社会。

This is called the “lookback time”, and it's a cru cial tool for cosmology: by observing very distant objects, we can see the Universe when it was young!

这叫做“回溯时间”，是宇学的一个重要工具：通过常遥远的物体，们可以看到宇时的样子！

In July, a fire at Iran's most important nuclear-fuel-enrichment site, which offi cials blamed on a bomb planted by Israel, inflicted enough damage to delay Iran's nuclear program by months.

今7月，伊朗最重要的核燃料浓缩设施发生火灾，造成的破坏足以使伊朗的核计划推迟数月。官员们将火灾归咎于以色列安置的炸弹。