Personally, the job as a teacher be challenging, for I sometimes deal with some smarter but less diligent students.
A. can; have to
B. may; can
C. has to; may
D. ought to; must
网友回答
A. can; have to
B. may; can
C. has to; may
D. ought to; must
解析：考查情态动词。句意：就个人而言，作老师的这个工作是很有挑战性的因为我有时不得不对付那些 聪明而不用功的学生。Can 表示表示能力（体力、知识、技能） may表示请求和允许 have to 不得不 ought to 应该。所以选A项。
考点 : 考查情态动词