+Conjugation is the regular arrangement of all the forms of the verb+.
+_Synopsis _is the regular arrangement of the forms of one number and person in all the modes and tenses+.
+_Auxiliary Verbs _are those that help in the conjugation of other verbs.+
The auxiliaries are do, did, have, had, shall, should, will, would, may, might, can, could, must, and be (with all its variations, see Lesson 135).
+The Principal Parts of a verb, or those from which the other parts are derived, are the present indicative or the present infinitive, the past indicative, and the past participle.+
List of Irregular Verbs. [Footnote: Grammarians have classed verbs on the basis of their form or history as Strong (or Old) and Weak (or New).
Strong verbs form their past tense by changing the vowel of the present without adding anything; weak verbs form their past tense by adding ed, d, or t. Some weak verbs change the vowel of the present; as, tell, told; teach, taught. These are weak because they add d or t.
Some weak verbs shorten the vowel of the present without adding anything; as, feed, fed; lead, led; and some have the present and the past alike; as, set, set; rid, rid. They have dropped the past tense ending.
The past participle of all strong verbs once ended in en or n, but in many verbs this ending is now lost.
Since most verbs form their past tense and past participle by adding ed, we call such Regular, and all others Irregular. Our irregular verbs include all strong verbs and those that may be called "irregular weak" verbs.