单选题 -- Jane, what do you think of Mr Green? -- As ______ teacher, he ought to set ______ good example to the pupils.

【正确答案】 B

【答案解析】考查冠词用法。teacher和example都是可数名词，都应用冠词修饰。此处它们都不是特指，所以都用不定冠词。