Here are some sites to help thoroughly learn about verbs:

Quia Verb phrases— go through 10 sentences and find the complete verb phrase
Verb Quest–This site has many links to sort through about grammar and verbs.
HyperGrammar (linking verbs)– The student takes a simple quiz decided which verbs are linking verbs. This is from a college website
HyperGrammar (Verb Tense)– This is a college quiz in which the student determines whether the verb is formed correctly in the sentence.
Be Verb quiz— This is a simple fun quiz to help students learn the verb tenses of Be.