题干
The old town has narrow streets and small houses _______ are built close to each other.
A：that
B：who
C：where
D：what
答案(点此获取答案解析）
A
The old town has narrow streets and small houses _______ are built close to each other.
A：that
B：who
C：where
D：what
3H2O+2CO2的认识，错误的是（ ）