题干
— ______ is Lingling doing?
— She is doing her homework. （ ）
A：What
B：Where
C：Why
答案(点此获取答案解析）
A
— ______ is Lingling doing?
— She is doing her homework. （ ）
A：What
B：Where
C：Why
对任意
，都有
，且当
时，
,
=" "