1.held hostage 劫持人质

The class was held hostage by a hooded gunman.

全班学生被一名蒙面持枪歹徒挟为人质)e@IAuoS*1DOXE.。

2.reckon 认为

Some people reckon that space exploration is a sheer waste of time and money while a majority of other people believe that it is of great importance.

有些人认为太空探索纯属浪费时间和金钱，但是大多数人认为太空探索有着非常重要的意义)|1^n4Joo4P]。

3.bounce off 弹开，反弹

Short sound waves bounce off even small objects.

短声波即使遇到小物体都会产生回音dyQrge@LDByE=4hA3D。

4.upshot 结果，结局

The upshot could be a much bigger bubble in the future.

结果可能是日后出现更大的泡沫.EbmHUL&YgXFu。