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题库 / Prep2007E2-SC-13
One of the earliest known birds with a beak and contour feathers, Confuciusornis sanctus, with large clawlike "thumbs" on its wings, which probably helped them to climb up to a launching position for flight.
with large clawlike "thumbs" on its wings, which probably helped them to
with large clawlike "thumbs" on their wings, which probably helped it to
had large clawlike "thumbs" on its wings, which probably helped them
had large clawlike "thumbs" on its wings, probably to help it
had large clawlike "thumbs" on their wings, probably to help it
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AB是没有谓语的问题
CE有it 和them不一致
D这里to do 是目的状语？
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