--It is really fun to hike and I often go hiking in the forest.--But hiking alone in the forest ______ be very dangerous.

Miss Li regards all her students _______ her children. 

You have finished most of the work, so you ______ start working so early tomorrow. You ______ come at 9:00.

—How much shall I pay for the telephone call? —You  _____. It's free.

When I was a child, I ______ watch TV whenever I wanted to.