【正确答案】The main objectives of opening and cleaning are: Separating fiber flocks, removing foreign matters, and blending all the fiber flocks together.
   The main objectives of carding are: Separating fiber bundles into individual, removing small dusts and lints, intimately blending fibers, evening the fibers and sliver, and forming of sliver.
   The main objectives of combing are: Removing the short fibers, removing trashes, especially the imperfections such as neps and slubs, and straightening and paralyzing the long fibers that are retained.