You can also use the -d switch to display each system call with a time delta, representing the elapsed time in seconds since the last event.
还可以使用- D开关显示每个系统调用的时间差，时间差表示自前一个事件以来流逝的秒数。
2
Don't get things mixed up, just the z component of the force becomes Gm triple integral of delta cos phi sine phi d rho d phi d theta.
不要搞混，只是力的z分量罢了,它是Gm∫∫∫δcosφsinφdρdφdθ
3
Cheng, Hong 1990. The Rural Commodities Market in the Yangzi Delta, 1920-1940: a Social and Economic Analysis. Ph. D. dissertation, Univ. of California, Los Angeles.