SAT三道语法题求助!

题目

SAT三道语法题求助!
A severe northeastern storm struck Boston on New Year's Day,1990,slowing down the loading of ships in the (harbor,the city was caught off guard because of the Weather Bureau being closed for the holiday.)答案是harbor,the city was caught off guard because the Weather Bureau was closed for the holidays.为什么不能写成harbor,catching the city off guard because the Weather Bureau was closed for the holidays.原句的struck是过过去式还是过去分词?
No one but a fool would readily lend money to a person who （is） known as a frequent gambler.答案说原句没有错,可是前面是would后面的is为什么不用改成was?
The plans proposed by the students for the homecoming celebrations are perfectly clear and （it is） well within our （budget,however,） the plans are not likely to be approved by the administration.答案说这个it is有错,错在哪儿?指代不明吗?还有,这句话的however为什么前后都可以接完整的句子而且不用把其中的一个逗号改成分号或者句号?

答案

1.我觉得应该是过去分词作定语.要是catching这个句子就没有谓语了.
2.would具体表示什么我说不上来（可能是will的委婉说法什么的）,但是这里would不表示过去.
3.因为前半句压根就没有单数名词所以一定不是it is,至于however的问题我跟你的想法一样,可能是他错了.