Although the causes of cancer_____, we do not yet have any practical way to prevent it.
| A．are being uncovered | B．have been uncovering |
| C．are uncovering | D．have uncovered |
It was half a year________my good friend returned to his hometown.
| A．before | B．since |
| C．that | D．when |
—When did you get home last night?
—It was almost midnight________we arrived home.
| A．that | B．before |
| C．since | D．when |
It saves time in the kitchen to have things you use a lot________easy reach.
| A．near | B．upon |
| C．within | D．around |
The questionnaire takes________ten to fifteen minutes to complete and can be used along with the assessment interview.
| A．mainly | B．punctually |
| C．approximately | D．precisely |
He stood up and________a smile to cover up his disappointment.
| A．hid | B．managed |
| C．refused | D．brought |