I _____thank you too much for all your help to my son while we were away from home.

“Where’s my book? I can’t find it”.“It _______ on your desk.”

—It's no easy task to catch a ticket on a website that receives 1 billion clicks daily.—I can't agree with you more. There ________ be errors for every single step.

The light is on in Mr. Green’s room. He _______ be at home.

Curious about the world around him, my son__   __ask me endless questions when he was young．