How many more decades will have to pass ____ scientists succeed in providing a cure for cancer?
| A．when | B．since | C．before | D．until |
It was dark when Mary went out. I wonder how she ______ through the black lane by herself.
| A．dared not to go | B．dare going | C．not dare go | D．dared to go |
Not until I ________ to work ____ how much time I had wasted.
| A．did begin; didn’t I realize | B．began; I realized |
| C．did begin; I realized | D．began; did I realize |
–--I play high-temperature Yoga in the gym every Sunday.
---- Good habit, but the air in the gym is bad ________.
| A．to be breathed | B．to breathe | C．breathing | D．being breathed |
___________ his poem, he didn’t dare to submit it to the professor.
| A．Not having polished | B．Having not polished |
| C．Not polished | D．Not being polished |
Completely ____________ computer games, he now doesn’t take classes.
| A．addicted to | B．being addicted to | C．Having addicted | D．to addicted to |