题干
I have ____ uncle in America. He is ______ English teacher.
A：a; an
B：an;a
C：an;an
D：an;the
答案(点此获取答案解析）
C
I have ____ uncle in America. He is ______ English teacher.
A：a; an
B：an;a
C：an;an
D：an;the
、报警器两端的电压
的变化情况是
