[单项选择]Although they plant trees in this area every year the tops of some hills are still ________.


A. blank
B. hollow
C. vacant
D. bare

[单项选择]Although they plant trees in this area every year, the tops of some hills are still
A. blank
B. hollow
C. vacant
D. bare

[单项选择]Though people plant many trees in this area every year, the top of some hills is still ______.
A) open C) empty
B) bare D) blank


A. Though people plant many trees in this area every year, the top of some hills is still ______.
B. open
C. bare
D. empty
E. blank

[单项选择]We were delighted to find the trees planted a year before ______ very tall.


A. growing
B. being grown
C. having been growing
D. grown

[单项选择]What happens to trees each year


A. Their tings get thinner and thinner.
B. They add a ring of wood.
C. Their rings get darker in color.
D. They become more valuable.

[单项选择]

Passage Five
Every year gray whales migrate from the Bering Sea in Alaska to the Baja Peninsula in Mexico.
Eleven gray whales have died in the San Francisco Bay in the last three weeks. No one knows why the whales are dying.
Last year 270 whales died along the whales’ migration route. Many people think starvation is the cause. This year the dead whales seem to have more blubber (fat) on them.
Twenty years ago, the gray whale was listed as an endangered species.
Some scientists think that the larger number of whales makes it hard to find enough food. More whales create more pressure on the food supply, a supply that some scientists say may have dwindled as a result of the warm waters of E1 Nino.
Most of the whales have been dead for many days before they are found and studied. This makes it hard to find the reason for death.
65 whales have been seen in the San Francisco Bay Area this year compared to 17 last year
A. the whales travel such a long distance
B. there are more whales than there used to be
C. the whale bodies are too old to study by the time they are found
D. the whales are endangered

[单项选择]Every year a number of students graduate from the school which will ______ new students the first week in September.
A. enroll
B. recruit
C. collect
D. reproduce

[单项选择]Every year each household in the United States discards approximately a ton of trash.
A. filler
B. garbage
C. paper
D. fuel