单项选择题

Experiments showed that ______.

A．birds are likely to get lost if there aren't man-made stars.
B．day-flying birds depend on the sun while night-flying birds depend on the stars
C．birds depend on the sun to guide them
D．birds depend on the stars to guide them

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热门试题

单项选择题

The word hazard in the last paragraph most probably means ______.

A．danger
B．enemy
C．frightening
D．punishment

单项选择题

When file destroyed a home during the Dark Ages, people ______.

A．felt that the fire was a punishment given by God
B．wished the brigade had arrived sooner
C．tried to stop heating by dried grass or wood
D．tried to know how and why the fire started