----- Why was the student laughed at by classmates?
----- He must have _____ what the teacher said in class.
| A．recognized | B．grasped | C．mistaken | D．achieved |
The refugee crisis（难民危机） in Europe, if ________ properly, can lead to serious social problems.
| A．not handled | B．not being handled |
| C．not to be handled | D．not having been handled |
It is generally cold and dry here in autumn, but sometimes, it ________ also be warm and rainy.
| A．may | B．should | C．must | D．can |
Thanks to the immediate measures taken by the central government, the economy of China ________ soon after the global financial crisis.
| A．took up | B．rose up | C．picked up | D．put up |
The difficulty lies in ________ they will come to our help immediately.
| A．whether | B．that | C．if | D．which |
It is recently reported that quite a number of applications ________ from Apple’s official APP. Store are not safe to use.
| A．downloading | B．downloaded |
| C．having downloaded | D．to be downloaded |