[請益] TPO 18 lightning

[zone0076 (不屬於人類的天堂)]

The formation of the channel is initiated when electrons surge from
the cloud base toward the ground. When a stream of these negatively
charged electrons comes within 100 meters of the ground it is met by
a stream of positively charged particles that comes up from the ground.
When the negatively and positively charged streams meet, a complete
channel connecting the cloud and the ground is formed. The channel
is only a few centimeters in diameter, but that is wide enough for
electrons to follow the channel to the ground in the visible form of
a flash of lightning. The stream of positive particles that meets the
surge of electrons from the cloud often arises from a tall pointed
structure such as a metal flagpole or a tower. That is why the subsequent
lightning that follows the completed channel often strikes a tall
structure.

Which of the following claims about lightning strikes can be
inferred from paragraph 5 ?

1.During a lightning strike the diameter of the channel the electrons
  follow is considerably enlarged beyond a few centimeters

2.A building is unlikely to be hit by lightning unless it is at least
  100 meters tail

3.A building is hit by a lightning strike because the building itself
  has first determined the path the lightning then takes to it

4.The light of a lightning strike first appears at the point where
  the streams of negative and positive particles meet

答案就是第四個  可是我找不出是從哪裡推出來的

可以麻煩解答一下嗎?! 謝謝

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推 fanghua:我的答案怎麼是3...不過我也不知道原因???
推 fongwha:我的版本答案也是3
推 crazyhsin:我的版本答案是4，我覺得答案是在when the negatively
→ crazyhsin:and positively charged streams meet, a complete
→ crazyhsin:channel connection to the cloud and the ground is
→ crazyhsin:formed. 這段說的channle應該等同"雷擊"的path
→ crazyhsin:哈不過是我自己寫題目時的推測～給你參考！