【单选题】The prefix Mach is used to describe supersonic speed. It was named for Ernst Mach (1838-1916), a Czech-born Austrian physicist, who contributed to the study of sound. When twice the speed of sound, it...
A.
the ratio of the air speed of an aircraft to the speed of sound.
【简答题】The drive shaft connects the transmission output shaft to the differential pinion shaft.Since all roads are not perfectly smooth, and the transmission is fixed,the drive shaft has to be flexible to ab...