—What should we do first if we want to develop our village?

        —A lot of new roads_____, I think.

       A. have to build     B. must build  C. must be built

---What should we do first if we want to develop our village?

---A lot of new roads ________, I think．

1. A.
   must build
2. B.
   have to build
3. C.
   must be built
4. D.
   have built

—What should we do first if we want to develop our village?
—A lot of new roads_____, I think.

1. A.
   have to build
2. B.
   must build
3. C.
   must be built