water changed into steam.A. Heated B. HeatingC. Being heatingD. to heat

问题补充：

, water changed into steam.

A. Heated

B. Heating

C. Being heating

D. to heat

答案：

(答案→)A. Heated

B. Heating

C. Being heating

D. to heat

解析：考查非谓语动词，句中逻辑主语与heat之间的关系为被动关系，故用过去分词，选A。