Strong verbs demonstrate a change of tense by a change of vowel in the stem (the MnE equivalents like 'sing, sang, sung' etc.) while weak verbs have no vowel change and instead demonstrate conjugate by changes in the suffix. There are three classes of OE weak verbs. Class III has only four members: the verbs for 'think', 'say', 'have' and... 'live', I believe. To say in OE is... 'secgan' (-an always signifies the infinitive form), 'have' might be 'habban' or that might be a different form, and I can't remember the others. I've got to brush up on this stuff in preparation for Beowulf. :D