iBT TOEFL Topic Vocabulary Breakthrough Unit 076

iBT TOEFL Topic Vocabulary Breakthrough Unit 076
Author: Li Xiaolai

76. Bird wings are highly modified forelimbs with a skeletal structure resembling that of arms. The shape of a bird’s wings influences its style of flight, which may consist of gliding, soaring, or flapping. Flight muscles are located in the chest and are attached to the wings by large tendons. The breastbone, a large bone shaped like the keel of a boat, supports the flight muscles.

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