VOA慢速英语:Apple’s Steve Jobs Takes Medical Leave; Next Google Chief Knows Company

例句：Some kinds of manual labour have been replaced by machines.
      有一些体力劳动已为机器所取代。

replace和sbstitute都表示替代的意思，不过用法上有所不同：

substitute的用法是：substitute A for B，意为用A代替B；

replace 的用法是：replace A with B，意为用B代替A。

例句：

1)In manufacturing, cheaper materials are constantly being substituted for the better and more expensive kind.
2.)The government decided to replace coal with gas.

2.form vt.vi.形成, 构成, 产生

例句：Steam forms when water boils.
      水煮沸之后就形成蒸汽。

3.associate v.在(思想、想像、感情、记忆等方面)把…联系在一起，联想(with)

例句：Many people associate dark clouds with depression and gloom.
      许多人把乌云与沮丧、阴郁联系起来。

4.tightly adv.紧紧地;坚固地;牢固地

例句：In her anger she compressed her lips so tightly that they went white.
      她生气时把嘴闭得很紧,嘴唇都变白了。

      James went to his daughter and hugged her tightly.
      詹姆斯走到女儿身边，紧紧地拥抱她。

5.rejoin v.重新加入

例句：Henry has apologized for his bad behaviour and should be allowed to rejoin the group with a clean sheet.
      亨利对他过去的不端行为表示歉意,如果今后不再重犯错误,应该被允许重新加入这个小组。

6.recapture v.再次经历、体验或产生

例句：He is trying in vain to recapture his past.
      他试图回忆以前的事情，但却枉然

      If I am once put off I find it very difficult to recapture the same train of thought.
      我一旦受到打扰,发觉自己很难回到原来的思路上来。