Someaspectsofapilot'sjob      beboring,andpilotsoften  ...

问题详情：

Some aspects of a pilot's job       be boring, and pilots often       work at inconvenient hours．

    A． can  ; have to                                B． may  ;  can                      

       C． have to; may                                            D． ought to; must

【回答】

A

知识点：情态动词

题型：选择题