207. Geologists believe that the Bering land bridge, over which human beings are thought to have first entered the Americans, disappeared about 14,000 years ago when massive glaciers melted and caused the sea level to rise several hundred feet worldwide. (A) are thought to have first entered (B) were thought first to enter (C) were thought at first to enter (D) are thought of as first entering (E) were thought to first enter
220. Because Halley’s comet changes orbit slightly during the seventy-six-year interval between passing close to Earth, it may veer onto a collision course with a planet sometime in the distant future. (A) between passing (B) of passing (C) between its passes (D) of its passes (E) as it passes
Agree. The present perfect tense can be used to describe events in the past. In an infinitive, it has to be changed to present perfect to express it.
補充一題： 218.The domesticated camel, which some scholars date around the twelfth century B.C., was the key to the development of the spice trade in the ancient world. (A) The domesticated camel, which some scholars date (B) The domesticated camel, which some scholars having thought to occur (C) Domesticating the camel, dated by some scholars at (D) The domestication of the camel, thought by some scholars to have occurred (E) The camel’s domestication, dated by some scholars to have been
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发表于 2003-11-10 23:33:00
