.
This kind of work ______ great patience, so you should take your time.
| A．calls on | B．calls for | C．calls up | D．calls back |
----- Why hasn’t Jack come back yet ? _______ anything have happened to him ?
----- I’m not sure, but I guess something _______ .
| A．May, must have | B．Can, may have |
| C．Must, may | D．Should, might have |
The big fire ________ due to the burning of construction materials caused 58 deaths and destroyed all the belongings of the people there.
| A．was believed to occur |
| B．was believed to have occurred |
| C．believed to have been occurred |
| D．believed to have occurred |
-----What’s one of the major problems _____ the children living in remote mountainous areas?
----- It’s poverty.
| A．face | B．facing | C．faced | D．faced with |
Doctors Without Boarders, ________ international organization, received ________ Nobel Prize for Peace in 1999 for its outstanding work .
| A．an, / | B．the, the | C．/, a | D．an, the |
It was several minutes ________ we realized what was happening—our dog was trapped in a newly－dug tunnel.
| A．since | B．before | C．until | D．While |