19、I’ve been keeping track of our phone bills.

注意的词语：keep track of：(明了、一目了然的意思)

20、I’ll have to call them and have them straighten it out.

注意的词语：straighten out：(改正、更正)

    1、He is famous for vigorously opposing the use of chemicals to kill pets.

这个句子中重点解析的是 vigorously opposing 并翻译这句话。

注意的词语：vigorously opposing积极反对

翻译为：他因为积极反对用化学品杀宠物而出名。

2、What would you recommend for a tenth-grader?

这个句子中重点解析的是tenth-grader到底是十年级的学生，还是十岁的小孩?

tenth-grade是"十年级"，所以tenth-grader当然是"十年纪的学生"了。十岁的小孩是：teenager