—What are you doing, John? Why stop?
—To be on the safe side, we’d fill up the car now for we _______ run out of gas on the way．
| A．must | B．will | C．might | D．should |
—I hear some noise in the next room.
—Oh, yes. Your sister_______ there.
| A．cries | B．is crying | C．cried | D．was crying |
All the students__________ to plant trees and there’s nobody in the classroom.
| A．go | B．will go | C．have gone | D．wound go |
Stop! A little boy_________ the street.
| A．is crossing | B．crosses | C．crossed | D．has crossed |
The girl________ to milk since last winter.
| A．learns | B．learned | C．has learned | D．would learn |
What__________ to you this morning?
| A．happens | B．is happened | C．happened | D．was happened |