中译英：她正坐在树下看书要突出坐和看 she is sitting under the tree and reading books reading books 中间我认为要加上the，变成 reading the books 或是reading a books 你们认为呢？

Now she reading a book under the tree

She is sitting under the tree and reading.没有必要加定冠词，不是强调哪一本书

She is reading the book under the tree.

tazaishuxiakanshu

she is sitting under the tree and reading books 。

She is reading books under the tree.

最好的表达应该是：
she is reading under the tree.
干净而地道.
首先reading本身就已经是“看书”的意思了,因此根本不需要什么reading book,更用不着讨论是否加定冠.除非它是特指某本书,如你所提的reading the books.但这里的“the books”这些书,一定是前文中提及的,也就是特指的.
其次,under the tree 便是在树下的意思,而用不着sitting.
所以,其它的表达在语法上并没有错,只是累赘而不地道.

she is sitting under the tree and reading books