17. (6 points) There is a project, if done alone, A needs 6 hours, B needs 8 hours, and C needs 10 hours. At 8 AM, the three of them start working together, but A has to leave in the middle. If the project is completed by noon at 12 PM, then A left at $\qquad$ AM $\qquad$ minutes.
【Solution】Solution: The efficiency of A, B, and C are $\frac{1}{6}, \frac{1}{8}, \frac{1}{10}$, respectively.
B and C work for a total of 4 hours, $\left(\frac{1}{8}+\frac{1}{10}\right) \times 4=\frac{9}{10}$, the total work done by A is: $1-\frac{9}{10}=\frac{1}{10}$,
The working time of A: $\frac{1}{10} \div \frac{1}{6}=\frac{3}{5}$ (hours), the working time of A is: $\frac{3}{5} \times 60=36$ (minutes),

A leaves at 8:36.
The answer is: 8:36.