单项选择题

According to the passage, which of the following statements is NOT true

A．Although birds preen, the feather wears out.
B．Two processes are involved in molting.
C．When most feathers have been replaced, then the molt is completed.
D．A bird seems unwell when molting.

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热门试题

单项选择题

Some birds that are molting maintain balance during flight by______.

A．constantly preening and caring for their remaining feathers
B．dropping flight feathers on both sides at the same time
C．adjusting the angle of their flight to compensate for lost feathers
D．only losing one-third of their feathers

单项选择题

According to the passage, many child-patients who stay a short time in hospital______.

A．catch up with the others quickly by themselves
B．ask the school to help them to study
C．ask their friends to help them to catch up with the others
D．ask the hospital teachers to help them to study