6．Be careful! The slightest spark（火花）could ______ the fireworks.
| A．set about | B．set off | C．set out | D．set up |
After _____ seemed an endless wait, it was her turn to enter the personnel manager’s office.
| A．that | B．what | C．which | D．whether |
_____ at in this way, the present economic situation doesn't seem so gloomy.
| A．Looking | B．Looked | C．Having looked | D．To look |
I arrived at the airport so late that I _____ missed the plane.
| A．only | B．quite | C．narrowly | D．seldom |
She refused to _____ the door key to the landlady until she got back her deposit.
| A．hand in | B．hand out | C．hand down | D．hand over |
_____ I sympathize, I can’t really do very much to help them out of the difficulties.
| A．As long as | B．As | C．While | D．Even |