某同学测出的声速值比正常高了一倍，原因可能是 The sound velocity measured by a student is twice as high as the normal value. The reason may be that

A.误将相位差为2π的一个波长的距离当成了相位差为π的距离 The distance of a wavelength whose phase difference is 2π is mistakenly taken as the distance with phase difference of π###SXB###B.误将相位差为π的一个波长的距离当成了相位差为2π的距离 The distance of a wavelength with a phase difference of π is mistakenly taken as a distance with a phase difference of 2π###SXB###C.逐差法计算时，忘了除以2 Forget to divide by two when calculating by the successive difference method###SXB###D.仪器设备问题影响了实验的测量结果 Environmenta