It’s difficult for such a girl to swim ____ the river.
| A．cross | B．across | C．crossing | D．crossed |
—Would you like to go out for a walk with us?
—,but I must finish my homework first.
| A．Of course not | B．That’s all right | C．Yes, I’d love to | D．Yes, I do |
I usually sleep with the window open _____ it’s very cold.
| A．until | B．unless | C．when | D．if |
We have to _________our school trip till next week because of the heavy rain.
| A．put off | B．put on | C．put up | D．put down |
The light is on in Mr. Green’s room. He _______ be at home.
| A．must | B．can | C．mustn’t | D．can’t |