电控汽油喷射发动机，是由电子控制器ECU控制点火系统，其点火提前角包括（）、基本点火提前角和（）三部分。
参考答案：初始点火提前角，修正点火提前角
如果+5m表示向东走5m，那么-14m表示______．
NUMBER OF FARMS IN THE UNITED STATES,
The average acreage per farm was approximately 140 in 1910 and 220 in 1950. The ratio of the total farmland acreage in 1910 to the total in 1950 was most nearly ？（）
A.A
B.B
C.C
D.D
E.E
