The old town has narrow streets and small houses are built close to each other.A. theyB. w

问题补充：

The old town has narrow streets and small houses are built close to each other.

A. they

B. where

C. what

D. that

答案：

A. they

B. where

(答案→)C. what

D. that

解析：考察主语从句。从句且缺主语,能做主语只有C what。