Some aspects(方面) of a teacher’s job ______ be tiring, and teachers often ______ work at inconvenient hours.

A．can; must

B．may; can

C．can; have to

D．have to; must

《联合国禁止非法贩运**品和精神药物公约》是国际社会第一个反洗钱国际法规范。