Multiple choice.

1. The difference was...small...be worth arguing about.

A. as/ as not to

B. so/ as not to

C. so/ as to not

2. He is...good an athlete ...worry about the try-out.

A. So/ as not to

B. such/ as not to

C. so/ as to

D. such/ as to

3. There is only Hoa in the classroom...some exercises.

A. does

B. To do

C. Is doing

D. Doing

Could you please as well point out the differences between the first two sentences to me?

Thank you very much.