问题补充：
that all mountain roads were closed.
A. So became the dangerous weather
B. So dangerous did the weather become
C. So dangerous became the weather
D. Dangerous the weather became so
答案：
A. So became the dangerous weather
(答案→)B. So dangerous did the weather become
C. So dangerous became the weather
D. Dangerous the weather became so
解析： 考查倒装句。So+ 形容词或副词放在句首使用部分倒装，借助于助动词，故选B。句意：天气变得如此的危险以至于所有的山路被关闭了。
