Sentence Correction

Well these are questions suppose to be made by an instructor and suppose to be as per GMAT standard

There are many but I dont quite agree with these
(as it is general,pardon me for posting all in once)

1)Carrying the hot water across the lane to melt the ice on the bird bath,the sparrows were gathered in the groups a few feet away
My choice:
bird bath,the groups of sparrow were gathering
OA
bird bath,i saw groups of sparrows gathered

Can we inject I in that way ...and it is passive as well


2)Like the hills that are found in Australia,the hills of USA
OA
Like those in Australia,the hills of USA

Isn't that 'those' a dangling modifier....what does that 'those refer to...
those can be house...any thing


3)Except for one class in sociology and on in humanities,all the student's graduation requirements have been fulfilled.
OA.
Except for one class in sociology and on in humanities,the student has fulfilled all of his graduation requirements

How can his.....that means only male students which changes the meaning of original sentence

4)The audience for the opera,an inventive rendition of Wagner's Tisolse,was clearly entharalled by the show for the attendees paused for some moments before applauding vigoursly at its conclusion
OA:A
ok audience is collective noun ie singular but doesnt this sentence gives the meaning that 'audience' and 'attendees' were two different thing...
even so ,as attendees applauded so audience was entharalled is illogical

5)Harry's "The Four seasons" remains among the most popular pieces of modern music;few people relaize that he wrote sonnets to accompany each of the four concertos.
OA:A
My choice:modern music but few people
whats problem in that
the sentence tends to show that contradiction



Please comment on these and help...
These were only (so called) mistakes i made in that set and i think these actually are not errors....

Please comment