Many countries are increasing their use of natural gas, wind and other forms of________.[      ]

A. energy  

B. source

C. power  

D. force

喷油始点决定于电磁阀断电时刻，喷油终点决定于（）。

A.压力传感器

B.预紧弹簧力

C.凸轮轴

D.共轨压力