Shops are open; people are at work. But many Poles are also asking questions such as why so many of the country's political leaders were traveling on one plane and why, if as Russian authorities say, the pilot ignored warnings against trying to land in poor weather conditions.

VOA: standard.2010.04.12

And so there are only two kinds of waves that can exist on this violin string, standing or traveling.

由于这只有两种波,可以存在在这条弦上，驻波或行波。

麻省理工公开课 - 固态化学导论课程节选

So fruitful is their land that they are spared the evil necessity of traveling on ships and there you have an interesting point about the Greeks.

他们的土地丰饶,这一切让他们远离了航行的厄运,这时你会发现关于希腊很有趣的一点

耶鲁公开课 - 古希腊历史简介课程节选