The Bunsen Burner is so named because it is thought ___________ by Robert Bunsen.
| A．to be invented | B．having been invented |
| C．invented | D．to have been invented |
Such a fierce dog _____ that we had to wait outside before we could get into his yard.
| A．has he had | B．did he have | C．he has | D．he has had |
An independent traveler would like to struggle with maps and signs ____ he finds the way．
| A．since | B．until | C．before | D．when |
As soon as his teacher begins lecturing, he begins to doze off, not intentionally but _______.
| A．personally | B．randomly | C．habitually | D．unconditionally |
The Chinese lunar New Year usually ______ two records: the world's most watched television gala show, and its busiest telecommunications network.
| A．develops | B．witnesses | C．establishes | D．launches |
The world famous director, three of _____ movies won Oscar awards, is reported to have retired.
| A．whose | B．which | C．whom | D．his |