He has devoted most of his time and energy _______ a cure for the disease.
| A．find | B．finding | C．to find | D．to finding |
Look over there—there’s a very long, winding path _____ up to the house.
| A．leading | B．leads | C．led | D．to lead |
I was out of town at the time, so I don’t know exactly how it _______.
| A．was happening | B．happened | C．happens | D．has happened |
So sudden ________ that the enemy had no time to escape.
| A．did the attack | B．the attack did | C．was the attack | D．the attack was |
Occasions are quite rare ____ I have the time to spend a day with my kids.
| A．who | B．which | C．why | D．when |
_____ was most important to her, she told me, was her family.
| A．It | B．This | C．What | D．As |