— Look it be Jack who is at the gate of the library.It be him. He has gone abroad.may;

问题补充：

— Look, it be Jack who is at the gate of the library.

It be him. He has gone abroad.

may; must B. must; mayn’t C. must; can’t D. can; mayn’t

答案：

解析：考查情态动词.may可以,must必须;一定,没有mayn’t这种说法,can’t不能;不可能.句意:看,在图书馆门口的一定是杰克._不可能是他.他已经去国外了.选C.最符合语境.