| 1. | Frequency is measured in hertz, or cycles per second .
频率用赫兹即每秒钟的周数来计算。 |
| 2. | The velocity of light is about 300,000 kilometres per second .
光速约为每秒30万公里。 |
| 3. | Its decay probability per second is the inverse of this time .
每秒的衰变几率是这个时间的倒数。 |
| 4. | The shaft and discs rotate at about forty revolutions per second .
竖轴和磁盘每秒钟大约旋转40转。 |
| 5. | The whole drum rotates at a steady speed of about sixty revolutions per second .
整个磁鼓大约以每秒60转的恒定转速旋转。 |
| 6. | The signals carried in copper wires consist of about one million waves per second .
在铜线中传送的信号是由大约每秒100万次波的电磁波所组成。 |
| 7. | A clock signal with 1 million pulses per second is referred to as a 1 megahertz .
每秒钟有一百万个脉冲及时钟信号，也称兆赫（）时钟信号。 |
| 8. | The fireball ascended with great rapidity, the initial rate of rise being about a mile per second .
火球以很高的速度上升，上升的最初速度约为每秒1哩。 |
| 9. | The filaments are expanding into space at a speed of roughly 5, 000 kilometers per second .
这些纤维状星云物质以每秒大约5000公里的速度向宇宙空间扩展。 |
| 10. | A light-year is the distance light travels in one year at a speed of 299, 792 kilometers per second .
一光年是光以每秒299792公里的速度在一年中所走过的距离。 |
