--Can the students in our class compare with those in theirs?

--The students in our class study ________ but not ________.

1. A.
   harder; as clever
2. B.
   hard; clever
3. C.
   hardest; cleverest
4. D.
   harder; cleverest

—Can the students in our class compare with those in theirs?

—The students in ours study       but not         .

A．harder ;as clever         B．hard ;clever         C．hardest ;cleverest D．harder ;cleverest