While working in the countryside , the students ________ a great deal of knowledge on plant life.
| A．looked up | B．picked up | C．put up | D．called up |
A cook will be immediately fired if he is found _____ in the kitchen.
| A．smoke | B．smoking | C．to smoke | D．smoked |
The traveler couldn’t make himself _____ in his poor English.
| A．understand | B．understanding | C．to understand | D．understood |
He rushed out of the burning house with the little boy in his arms ____________ the roof fell down and the boy was saved.
| A．after | B．as | C．before | D．until |
A new supermarket ______ here. They hope to finish it next month.
| A．will build | B．is built | C．has been built | D．is being built |
--- I’ll tell Mary about her new job tomorrow.
--- What? You ______ her last week.
| A．ought to tell | B．must have told | C．might have told | D．should have told |