—Bob, where is Linda?—She          be in the library, but I am not sure.

——Do you know where David is? I couldn’t find him anywhere. ——Well, he_______ gone far—his coat’s still here.

Johnny, you _________play with the knife, you_________ hurt yourself. 

Whenever my grandmother calls just to chat with me，I drop everything and enjoy the moment，knowing these times__________pass．

I ________ use a clock to wake me up because at six o’clock each morning the train comes by my house.