-How do you feel about the film?

-It is very ______. I have seen it for three times.[ ]

A. surprising

B. exciting

C. boring

具有多种能源的城市，为提高一次能源利用率与热效率不宜采用（）作为空调的冷热源。

A.电+燃气

B.单一的电

C.电+蒸汽

D.电+油