下列不属于点火系统控制的内容是（）
A.爆震控制
B.闭合角
C.喷油量
D.点火提前角
参考答案：C
12的因数有______，42的因数有______，12和42的最大公因数是______．
Don't worry. I can look after your pet ___ while you are away. [ ]
A.careful enough
B.carefully enough
C.enough careful
D.enough carefully
