问题
选择题
Carbon dioxide ___ from burning fuels is the most common of the so-called greenhouse gases.
A．producing
B．having been produced
C．to be produced
D．produced
答案
答案：D
此题为非谓语动词的考查,因为carbon dioxide 与produce 之间是动宾关系,所以 用过去分词表示被动。故选D。