I found ( ) impossible for ( ) to answer such a question in so short a time.
(A)it; he
(B)that; he
(C)that; him
(D)it; him
I dislike ( ) when you speak loudly in public.
(A)that
(B)what
(C)this
(D)it
He found ( ) very interesting to ride a horse.
(A)this
(B)that
(C)it
(D)which