lost track of

他忘记了自己读了多少本书。

He ___lost ___track ___of the number of books he read.

我们看电影时忘记了时间。

We ___lost ___track ___of time while watching the movie.

他在做白日梦，完全没跟上老师在说什么。

He was daydreaming and completely ___lost ___track ___of what the teacher was saying.