We cannot accurately predict how much carbon dioxide( )by factories will remain permanently in the air.
A、
released
B、
to release
C、
releasing
D、
being released
【正确答案】:A
【题目解析】:
carbon dioxide(二氧化碳)和release(释放)之间是被动关系,不选BC,这里并不强调正在被释放,所以选A。句意:我们无法准确预测有多少工厂释放出的二氧化碳将永久留在空气中。