"我想回家"是 I want to go home，不是 I want go home。want 后面必须带 to，这就是不定式 to do。
后面直接接 to do 的动词
小学到初中高频的这几个：
- want to do 想做
- hope to do 希望做
- wish to do 希望做
- decide to do 决定做
- plan to do 计划做
- would like to do 想要做
- agree to do 同意做
- learn to do 学着做
- promise to do 承诺做
- refuse to do 拒绝做
带人的结构：动词 + sb + to do
- ask sb to do 请某人做
- tell sb to do 告诉某人做
- want sb to do 想让某人做
- would like sb to do 想让某人做
- invite sb to do 邀请某人做
- tell sb not to do 告诉某人别做
疑问词 + to do
- I don't know what to do. 我不知做啥。
- She can't decide where to go. 她定不下去哪。
否定形式
not to do：
- He decided not to go. 他决定不去。
口诀：想希望决计划，同意学承诺拒绝；ask tell 加人后，to do 跟在屁股后。
