a runner in a race的用法和样例：
- A false start in a race is when a runner leaves the starting line too soon.
- Anchor: The last runner in a relay race.
- A runner exercises before a race to prevent his muscles from tensing up.
- Yes, I do. I was a runner in school.
- Measure the time taken by(a runner,etc.or for(a race,process,etc.