1,SeatingonthegroundwastheonlyforeignerthatIsawattheparty.

　　seating怎么改?为什么?

　　答：Seated/Sitting

　　因为seat和dress一样,跟人作宾语.Heseatedhisson/himselfonthechair.

　　-->Hisson/Hewasseatedonthechair.

　　Hewassittingonthechair.不用说了吧,熟悉句子.

　　这句话为了平衡,倒装了.不倒装,则为Theonlyforeigner(定语从句)wassitting/seatedontheground.

　　2,Ican'tjudgebythatIknowofhim.

　　that怎么改?为什么?

　　答：what=thethingsthat.

　　whatIknowofhim=thethingsthatIknowabouthim.

　　我不能通过我了解他的那些情况来判断.

　　3,Withdayswenton,theweathergotworse.

　　with怎么改?为什么?

　　答：Asdayswenton,...

　　随着日子一天天过去,天气变得越来越差.

　　as是连词,可以跟时间状语从句.还有一种改法：Withdaysgoingon,...