Solve the problem:
1, the quantitative relationship of solving problems: elapsed time = end time-start time.
2. Common sense: Write homework and finish it quickly in less time.
3. The quantitative relationship of problem solving: start time = end time-elapsed time.
Error-prone questions:
This question examines the mastery of the timing writing method of electronic watches. The format is "hours: minutes", such as 0 1:23). Numbers less than 10 should start with zero. So this question is wrong. The correct spelling is 12: 05.