The two girls are so alike that strangers find difficult to tell one from the other.A. it

问题补充：

The two girls are so alike that strangers find difficult to tell one from the other.

A. it

B. them

C. her

D. that

答案：

(答案→)A. it

B. them

C. her

D. that

解析：那两个女孩太像了，很难分清她们谁是谁.

it 可以指代物也可以作为形式主语指代前面提到的事物或句子. it是形式宾语.选A