Add my answer to Exercise 4.28.

Included are the following 6 files:

	Exercise_4.28.pdf
	Exercise_4.28.tm
	Lazy_Evaluator.scm
	Lazy_Evaluator_(Variant).scm
	Test_for_Lazy_Evaluator.scm
	Test_for_Lazy_Evaluator_(Variant).scm

Thank you!
							Lawrence X. Amlord
							  Feb 23rd, 2013
							  Fuzhou, China
Add my answer to Exercise 4.29.

Included are the following 6 files:

	Exercise_4.29.pdf
	Exercise_4.29.tm
	Lazy_Evaluator_(with_Memoization).scm
	Lazy_Evaluator_(without_Memoization).scm
	Test_for_Lazy_Evaluator_(with_Memoization).scm
	Test_for_Lazy_Evaluator_(without_Memoization).scm

Thank you!
							Lawrence X. Amlord
							  Feb 24th, 2014
							  Xi'an, China