Lesson 21   More assimilated prefixes

ad +	preciate	= appreciate	com +	respond	= correspond
ad +	petite	= appetite	com +	rection	= correction
ad +	paratus	= apparatus	in +	rigation	= irrigation
ad +	parently	= apparently	in +	regular	= irregular
ad +	propriate	= appropriate	in +	ritate	= irritate
ad +	proximately	= approximately	in +	legal	= illegal
ob +	ponent	= opponent	in +	lustration	= illustration
ob +	portunity	= opportunity	com +	lapse	= collapse
sub +	ported	= supported	com +	lege	= college
sub +	posed	= supposed	com +	lection	= collection

1.	With what letter do all of the roots in the first column begin? _____ When joined to a root that begins with the letter p the prefix ad is spelled _____, the prefix ob is spelled _____, the prefix sub is spelled _____.
2.	Look at the words in the second column. When joined to a root that begins with the letter r the prefix com is spelled _____. the prefix in is spelled _____. When joined to a root that begins with the letter l the prefix in is spelled _____, the prefix com is spelled _____.

Lesson Generalization Assimilated prefixes often result in double consonants that cause spelling problems. The spelling of the prefixes ad, ob, and sub changes when they are joined to roots or base words that begin with the letter p: ad becomes ap ob becomes op sub becomes sup The spelling of the prefixes com and in changes when they are joined to roots or base words beginning with the letter r: com becomes cor in becomes ir   The spelling of the prefixes com and in changes when joined to the letter l: com becomes col in becomes il

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