赞题库-背景图

单项选择题

Prior to the formation of a tornado,_________.

A．the sky is cloudy
B．the sky is very dark
C．the sky is cloudless
D．a black line stretches across the horizon

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热门试题

单项选择题Why does breathing become difficult for humans during a tornado

A．The wind becomes fast and hot.
B．Air pressure gets steadily lower.
C．The black area moves closer.
D．They are knocked to the ground.

单项选择题Which of the following is NOT the result of a tornado

A．Insects are unable to balance themselves.
B．It is difficult to breathe.
C．A tornado destroys everything on its path.
D．A tornado kills 120 people every time it comes.