____________caused the accident is still a mystery.
| A．How | B．What | C．That | D．Where |
——Why are the housing prices in big cities going up all the time?
——One reason is that people are__________ into overcrowded cities in great numbers.
| A．breaking | B．filling | C．pouring | D．hurrying |
The woman sold the eggs ________ seven dollars and they were sold ________ half price.
| A．with, at | B．for, at | C．at, in | D．by, on |
I’ve kept up a friendship with a girl whom I was at school ________ twenty years ago.
| A．till | B．with | C．about | D．since |
In the experiment we kept a watchful eye ________ the developments and recorded every detail.
| A．in | B．at | C．for | D．on |
Books are the most important records we keep ________ man’s thoughts, ideas and feelings.
| A．up | B．of | C．for | D．on |