oxford_guide_to_english_grammar

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84 The ordinary verb be
83 Auxiliary verbs and ordinary verbs
1 In these statements, be and have are auxiliary verbs.
Continuous: I'm taking my library books back.
Passive: Books are lent for a period of three weeks.
Perfect: I've finished this book.
In a statement we do not normally use the auxiliary do. Verbs in the present simple
or past simple have no auxiliary.
Simple: I like murder stories.
2 In negatives, questions and some other patterns, we always use an auxiliary. In
simple tenses we use the auxiliary do.
be/have
Negative I'm not going to I don't go to the library
the post office.
very often.
Question and Have you finished Do you use the library? ~
short answer this book? ~ Yes, I have. Yes, I do.
Tag You're reading You like murder stories,
this book, aren't you? don't you?
Addition I've read this book. I enjoyed that book.
~ So have I. ~ So did I.
Emphasis I am enjoying this book. I do like murder stories.
• 51(2)
do
3 Be, have and do can also be ordinary verbs.
It was a lovely day. We had some sandwiches. (= ate)
I did the crossword this morning. (= completed)
The ordinary verbs can be perfect or continuous.
It has been a lovely day. We were having some sandwiches. (= were eating)
I've done the crossword. (= have completed)
NOTE
a There can be the same auxiliary and ordinary verb together.
I was being lazy. (continuous of be) I've had a sandwich. (perfect of have)
I did do the crossword yesterday. (emphatic form of do)
b The ordinary verb do can be passive.
The crossword was done in ten minutes.
84 The ordinary verb be
1 Be as a linking verb
The ordinary verb be functions as a linking verb. • 9
The world is a wonderful place. The prisoners were hungry.
Are you being serious? The boss has been out of the office.
For there + be, • 50.