单项选择题 The view that the yield of rice remains steady is by no means______, owing to the fact that yearly tempests overflowing Asia influence it in______manner.（）

单项选择题 An enthusiast of sprightly music, Mendler surprised us all by proclaiming the final piece on the concert program, a lugubrious______as his favorite.（）

单项选择题 Performing rote memory exercises rarely improves the______of any given subject, but______may nevertheless be useful to the student preparing for an examination.（）