流量测量一般都无法直接得出流量值，而是利用流速，压差等参数计算出来的。
参考答案：对
—Tom, have you seen your brother?
—Oh, I saw him ________ basketball on the playground on my way home. [ ]
A. to play
B. plays
C. playing
D. played
为什么说犯罪学是多学科交叉的独立的综合性学科？
