_____ a teacher, John thinks that his main duty is to help the students become better learners.[ ]

I always go to sleep _____the light on because I amafraid of the dark when I am alone in a place. [ ]

Mr Li, I found a watch on the playground.-You should try to find out ______.

He is a swimmer, and he swims very _____________ .

Millie, where is Miss Li?—She a speech on Chinese art to the first-year students in the hall.