Research shows that humans ______ from selfish to unselfish behavior when they are watched.
| A．tell | B．switch | C．range | D．distinguish |
I often see lights in that empty house. Do you think I ______ report it to the police?
| A．should | B．may | C．will | D．can |
--- I don't mind telling you what I know.
--- You ______. I'm not asking you for it.
| A．mustn't | B．may not | C．can't | D．needn't |
Coal is hard, like a rock and yet it burns, while no rocks ______.
| A．do | B．does | C．are | D．is |
--- John, where are the cookies? Don’t tell me you ate them all!
--- ______ I couldn’t help it. They were so good.
| A．Yes, I did. | B．No, I didn’t. |
| C．Yes, I have. | D．Why? Sounds strange! |
--- How will I ______ you at the station?
--- Well, I’m wearing a hat and I’ve got a big black umbrella with me.
| A．recognize | B．notice | C．see | D．realize |