1. for the first time 是作为状语提前了,要不看起来别扭的话,你可以放到句尾：________ in years their team won the World Cup for the first time .
2. As “正如”,句子中间要有逗号,逗号后是完整的一句话
It做主语的时候,句子是强调句,可以把it+be...that 结构给去掉,句子依然完整,你试试看.
3.B. whose ,表示从属关系,“洪水的影响”
相当于：from the effect of which
4.用that 或者which 均可,原因是后面 visited 是及物动词,可以用visit the chicken farm.