51. In the low latitude area, it is usually very _____ all the year around.
| A．warm | B．hot | C．cold | D．Heat |
It is reported that the United States uses __________ energy as the whole of Europe.
| A．as twice | B．twice much as |
| C．much twice | D．twice as much |
As a result of the poor environment, many animals have __________.
| A．died away | B．died down |
| C．died out | D．died of |
Once you have become __________ to cigarette smoking or alcohol, it is hard to __________ it even though you try hard.
| A．used; get away with | B．addicted; get rid of |
| C．adapted; get down to | D．accustomed; get off |
His collection of ancient pots, old uniforms of the kings and splendid wedding dresses of royal family __________ a large fortune.
| A．are worth | B．is worthwhile |
| C．is worth | D．are worthwhile |
Nuclear energy __________ be really dangerous at times even though it's a nice energy in general.
| A．shall | B．should |
| C．can | D．must |