Update my answer to Exercise 3.31.

Modified are the following 2 files:

	Exercise_3.31.pdf
	Exercise_3.31.tm

Thank you!
							Lawrence X. Amlord
							  Oct 22nd, 2013
							  Xi'an, China
Update my answer to Exercise 3.31.

Modified is the following file:

	Exercise_3.31.scm

Thank you!
							Lawrence X. Amlord
							  Oct 22nd, 2013
							  Xi'an, China
Update my answer to Exercise 3.31.

Modified are the following 2 files:

	Exercise_3.31.pdf
	Exercise_3.31.tm

Thank you!
							Lawrence X. Amlord
							  Oct 23rd, 2013
							  Xi'an, China