初中to do sth 短语归纳如下：
一、to do sth是动词不定式形式，to的后面要接动词的原形。
I want to drink some water。我想喝些水。
Tell her not to be late tomorrow。告诉她明天不要迟到。
二、To是介词后面要接名词或者代词宾格形式。
He goes to school by bus every day。
他每天乘坐公交车上学。
They went to the park yesterday。他们昨天去公园了。
Please give two books to her。请给她两本书。
三、to doing中to是介词，所以它的后面要接动名词doing形式。
get down to doing sth。开始认真思考，着手处理某一些事情。
His son decided to get down to studying in the classroom。他儿子决定静下心来在教室里学习。
I must get down to reading this book。
我必须静下心来好好阅读这本书了。
look forward to doing sth.盼望做某事
My father and I Look forward to seeing you next month。
我爸爸和我都盼望着下个月能看见你。
We’re looking forward to meeting you again。
我们都盼望再次看见你。
Be used to doing sth.习惯做某事。
I am used to doing housework/cleaning the window with it。
我习惯于做家务活/用它清理玻璃。
I am not used to staying up too late。
我不习惯熬夜太晚。
Pay attention to doing sth注意去做某件事情。
He pretended to pay attention to listening the teacher。他假装在注意听老师讲课。
We must pay attention to listening to the lecture。我必须去倾听演讲。
Stick to doing sth坚持做某事情。
I think I‘ll stick to doing exercises every day。
我想我将坚持天天锻炼。
You should stick to eating some vegetables/ lighter foods。
你应该坚持吃蔬菜/清淡的食物。