同样都是平均速度，咋就不一样泥。
[font=Times New Roman][size=3]Q35: Data Sufficiency
Stations [i]X[/i] and [i]Y[/i] are connected by two separate, straight, parallel rail lines that are 250 miles long.
Train [i]P[/i] and train [i]Q[/i] simultaneously left Station [i]X[/i] and Station [i]Y[/i], respectively, and each train traveled to the other’s point of departure.
The two trains passed each other after traveling for 2 hours.
When the two trains passed, which train was nearer to its destination?
(1) （1）At the time when the two trains passed, train [i]P[/i] had averaged a speed of 70 miles per hour.
(2)
Train [i]Q[/i] averaged a speed of 55 miles per hour for the entire trip.
答案是A
我不解的是 A和B不都是给的平均速度吗，为啥就一个能解，一个不能解呢、。。
[/size][/font] it is average speed that is matters, it is when the average speed is detected.
For the average 70 miles an hour train P, it was detected by the time they met, which means that the meeting point of the trains are 140 miles away from Station X. So P is nearer to Y with only 110 miles left.
But for the second one only, we are not sure the location of Q.
So these two conditions are totally different, as the question focus on the meeting moment only 咳，还带这样考得。。。。。不过，还是谢谢啦
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