speed不是不可数嘛,那么at a high speed 又怎么说呢、、、

speed不是不可数嘛,那么at a high speed 又怎么说呢、、、 ar top speed为什么不说at a top speed with a high speed 还是at a high speed?China has developed -- such a high speed. i think it runs ____ a speed of 100km/h.A.in B.at C.away the train passed at a terrific speed At a fantastic speed Fantastic是什么意思? The car was seen travelling at a speed of 150km/h shortly .为什么此句用travelling呢. a car travelled at a speed of 90km/h.it left town ponpon at 11.00a.m.what time will it reach town dondon which is255km away? 速度快是at a high speed 还是at the high speed at high speed 还是at a high speed,教材上是前一种两者区别是什么? at the speed of 和at a speed of的不同RT! at high/fast speedat high speed or at fast speed,要不要加a The distance between city A and city B is 100 km.A car travels from city A to city B at a constant speed of x km/h and returns at a constant speed of y km/h,Express the time taken for the whole journey in x and y.time taken=distance tracelled/speed spread at a fast speed?介词用什么?at? at speed 还是at a speedNCE3 LESSON 25 at tremendous speed 用法没错吧 但为什么at a speed也对?区别在哪里呢 A car is travelling at a speed of 50km/h.How long will it take to travel a distance of 175 km?翻译和答案. The train traves at a speed of 80 kilometres per hour 向划线部分(at a speed向at a speed of 80 kilometres per hour 提问 If the distance from A to B is 500m,and Bobby runs at a speed of 6km/h,so the time she spent is____