Reading, Writing, etc.
Here are some resources for learning more about and practicing the use of infinitive phrases (along with gerunds and participial phrases)
1) Perdue Online Writing Lab - Excellent information resource. The examples and explanations here are clear. (no exercise) owl.english.purdue.edu/owl/resource/627/03/
2) The Tongue Untied - information on infinitives; links to information on other phrases; links on right hand side to practice exercise and online quiz www.grammaruntied.com/phrases/InfinitiveP.html
3) Towson University- exercise on infinitives www.towson.edu/ows/exerciseinfinitives.htm
4) exercise on recognizing infinitive phrases members.cox.net/lenco1/grammarpractice/infinitive/infinphrase.htm