The short wave signals bounce off the ionosphere that surrounds the Earth,back to the ground and then back to the ionosphere.

VOA: special.2010.12.08

So poor Lily is also an orphan, at least in the emotional sense, if not in actual reality. Her father, of course, had run off from her mother right after she had gotten pregnant, and then I suppose he came back.

可怜的莉莉也是个孤儿，至少从感情的角度上看是,如果你认为在现实情况不是，她的父亲，当然，在她母亲怀孕后,就开溜了，然后我猜测他又回来了。

耶鲁公开课 - 1945年后的美国小说课程节选

because someone turned the gas off and turned it back on and then left.

因为有人把瓦斯关了以后，又打开，忘记关上就离开了。

Make sure 课堂 - SpeakingMax英语口语达人