重点讲解：

1. thanks to 幸亏；归因于；

Thanks to the automobile, Americans soon had a freedom of movement previously unknown.

由于有了汽车，美国人很快就获得了前所未有的行动自由j1ZUZmG7nc~EDc2&KS。

2. have a handle on （理解、解决问题的）方法，途径；

This one was a doozy but we think we finally have a good handle on it now.

这个问题有点麻烦，不过我们认为现在已经能很好的处理它了b;&r4aNbLE9pX05y(r-。

3. react to （作出）反应；回应；

Someone allergic to milk is likely to react to cheese.

对牛奶过敏的人可能对奶酪也有不良反应O7W0K(bwy#oK~b]%lF|&。

4. rely on 依赖；依靠；

Many animals rely on concealment for protection.

许多动物靠藏匿自己来避害5cWdgb3I7,ddUmYJxb;h。