1．Tornadoes（龙卷风） are one of the worst weather events on earth．Each year，tornadoes kill many people．The storms often carry homes，cars and trees from one place to another．And they can also destroy anything when they pass by．
A tornado comes from a thunderstorm（雷雨） in the sky down to the ground．It is big at the top and small at the bottom．
A tornado appears when winds in different directions meet in the cloud and begin to turn in circles．People can see tornadoes almost everywhere in the world．But most happen from late winter to middle summer．There is a second high season in November．During spring，warm air moves north and mixes with the cold air left from winter．In November，the opposite happens．Cold air moves south and mixes with the warm air left from summer．
Tornadoes always come suddenly．Weather scientists have done something to predict（预测） tornadoes．But the storms often move too fast for people to protect themselves．Last year，tornadoes killed more than one hundred people in United States．
Scientists say the best place to be in is a small room，without windows，in the middle the lowest part of a building when tornadoes come．
根据短文内容，选择最佳答案．
66．According to the passage，we know the shape of the tornadoes may be likeB．
67．In the United States，most tornadoes happenD．
A．from late summer to middle summer
B．from late autumn to middle winter
C．from late autumn to middle spring
D．from late winter to middle summer
68．According to Paragraph 4，tornadoes appear whenA．
A．warm air and cold air mix
B．cold air and cold air mix
C．warm air and warm air mix
D．warm water and cold water mix
69．What's the Chinese meaning of the underlined word"destroy"？C
A．保护
B．珍惜
C．毁灭
D．惩罚
70．From the passage，we know thatB．
A．the United States has very few tornadoes
B．tornadoes are one of the worst weather events in the world
C．people should stay in big rooms with windows when tornadoes come
D．more than one thousand people were killed by tornadoes in the USA last year．
