The citizens of Beijing are proud of they have done to make Beijing a beautiful city.A. t

问题补充：

The citizens of Beijing are proud of they have done to make Beijing a beautiful city.

A. that

B. which

C. what

D. how

答案：

A. that

B. which

(答案→)C. what

D. how

解析：考查宾语从句，what引导宾语从句，在宾语从句中做done的宾语，句意;北京的公民对他们为了是北京成为美丽的城市所做的感到自豪。选C。