—You have no idea how to solve this math problem.
—You should try to think about which principle can _______ it.
| A．submit to | B．apply to |
| C．commit to | D．refer to |
After suffering a heart attack, Michael Jackson was pronounced dead, ____ a tragic end to the world' s most popular entertainer.
| A．to mark | B．marking | C．marked | D．having marked |
The magnificent tower must be saved, ________ the cost!
| A．however | B．whichever | C．whatever | D．wherever |
After supper she would sit down by the fire, sometimes _____ an hour, thinking of her young and happy days.
| A．as soon as | B．as much as | C．as many as | D．as long as |
People were not allowed to enter the reading room because it _______.
| A．had been painted | B．was being painted |
| C．was painting | D．painted |
．_____ alone in the large house, the little boy had to learn to survive by himself.
| A．To leave | B．Leaving | C．Left | D．Being left |