初级语法 Unit 23 be / have / do in present and past tenses

auxiliary verbs

(/ɔːɡˈzɪl.i.ə.ri/)

[Grammar] Helping verbs (be, have, do) used with a main verb to show tense or voice;

e.g.,

• I am working.

• He has finished the task.

• They do not know.

continuous aspect

[Tense] Uses "be + -ing" to show an action is in progress;

e.g., They were eating when I arrived.

passive voice

[Voice] Uses "be + past participle" to show what happens to the subject;

e.g., The room is cleaned every day.

perfect aspect

[Tense] Uses "have + past participle" to link a past action to another time;

e.g., I have lost my key.

operator "do"

[Syntax] The auxiliary used to form questions and negatives in Simple Present and Past;

e.g., Did you see my brush?

morphological change

[Linguistics] How verbs change form based on time and person;

e.g.,

infnitive	past simple	past participle
break	broke	broken
choose	chose	chosen
speak	spoke	spoken
wake	woke	woken
steal	stole	stolen