单项选择题

Some birds like to sit on a sheep because ______.

A．they can eat its parasites
B．they enjoy travelling with the sheep
C．they depend on the sheep for existence
D．they find the position most comfortable

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热门试题

单项选择题

We learn from the text that corals depend on plants for______.

A．comfort
B．light
C．food
D．oxygen

单项选择题

The underlined word they in the last sentence of the first paragraph refers to______.

A．birds and parasites
B．birds and sheep
C．parasites and sheep
D．sheep, birds and parasites