重点讲解：
1. hit on
突然想出（主意或解决办法）；
eg. After running through the numbers in every possible combination, we finally hit on a solution.
将这些数字进行各种可能的排列组合后，我们终于找到了答案。
eg. She was scared he might hit on the truth.
她非常怕他或许会无意中发现事实真相。
2. pull off
成功完成，做成（困难的事情）；
eg. It will be a very, very fine piece of mountaineering if they pull it off.
如果他们能成功，那将是一次非常了不起的登山壮举。
eg. Corporate turnarounds are painful ungainly and notoriously difficult things to pull off.
众所周知，要想完成企业好转的过程是痛苦而艰难的。
3. be serious about
认真的；当真的；真心的；郑重其事的；
eg. He was serious about the matter.
他对于那件事很认真。
eg. That boy is seldom serious about anying. He's always clowning aroud.
这个男孩对任何事情都不认真，他总是胡闹。

名人经典：
If you take the power-generating capability of an automobile and you compare that to the electric grid in the United States, it turns out that 4 percent of the automobiles, the power in 4 percent of the automobiles, equals that of the electric grid of the US. that's a huge power-generating capability, a mobile power-generating capability.
如果你比较汽车和美国电网的发电能力，结果就会发现汽车电力的百分之四相当于美国电网的供电能力。由此可看出汽车发电能力的强大，而且还是可移动的发电。