Collins Cobuild English Grammar (215 page)

to refer to something that you believe is still valid

The two theories
are
known as ‘ridge push’ versus ‘slab pull’ respectively.

to state continuing objectives

The aim
is
to direct the energy of the radiation to kill the cancerous cells.

to describe general principles or laws

When water
freezes
, it
expands
.

to explain or discuss data or results.

The results
show
that only a portion of world trade is affected.

to make reference to or relate events in literary works, films, etc.

Shakespeare, in King Lear,
emphasizes
the social causes of madness.

the present perfect

The
present perfect
is commonly used in the following ways.

to review research

There is a vast literature looking at development issues, the main elements of which
have been reviewed
here.

to make a general statement about the state of research activity in a given area

Little research
has been done
on microscopic plastics.

to summarize a text

In light of the evidence that
has been reviewed
thus far in this book…

the past simple

The
past simple
is commonly used in the following ways:

to indicate that something happened or was true at a particular time in the past, and that it may be less valid today

The almost universal view
was
that the liver was the main organ in the blood system.

to describe samples and procedures

A full study
was
conducted with a sample of managers from the UK head office.

to report findings

Their research
showed
that over half of all cancer cases could be prevented.

will

Will
is used to state your intention.

This study
will
examine the effects of depression.

Will
often occurs with an adverb such as
often
or
probably
, because academic writers must avoid suggesting that their personal ideas and theories are facts.

The desert regions
will probably
become more extensive.
Changes in practice
will often
be the result of a long political process.

linking verbs

Linking verbs
are used for describing a situation or a quality, and so they occur frequently in academic English. Linking verbs that are commonly used in academic English are
be
,
become
,
look
,
remain
,
seem
,
appear
,
prove
, and
represent
(see
3.126
to
3.181
).