Conditionals: other expressions (unless, should, as long as)
from English Grammar Today
Unless
Conditional
clauses can begin with unless. Unless means
something similar to ‘if … not’ or ‘except if’.
The
verb forms in the examples are similar to sentences with if:
we use the present simple in the unless-clause
and shall, should, will, would, can, could, may or might in
the main clause:
Unless I phone you,
you can assume the train’s on
time. (If I do not phone you /except if I phone you, you
can assume the train is on time.)
We’ll
have to cancel the show unless we sell more
tickets at the last minute. (We’ll have to cancel the
show if we do not sell more tickets/except if we sell more tickets
at the last minute.)
Warning:
We
don’t use unless for impossible conditions:
If the
government had not raised food prices, there would
not have been so many protests.
Not: Unless
the government had raised food prices …
Warning:
We
don’t use unless and if together:
We’ll
go to the coast tomorrow unless it rains.
Not: We’ll
go to the coast tomorrow unless if it rains.
See
also:
Should you (Should with inversion)
In
formal situations, we can use should + subject (s)
+ verb (v) instead ofif:
Should you wish
to cancel your order, please contact our customer service department
on 02317 6658932. (or If you should wish to cancel
your order …)
Should your
child become anxious or nervous about any activity,
it is a good idea to inform the team-leader. (or If
your child should become …)
Had you (Had with inversion)
In
formal situations, we can use had + subject + verb
instead of if in third conditional sentences:
Had I known
you were waiting outside, I would have invited you to come in. (If
I had known you were waiting outside …)
Had Margaret realised
she would be travelling alone, she would never have agreed to go.
If + were to
In
formal situations, we can use if + were to when we
talk about things that might happen but which we think are unlikely:
If the
Prime Minister were to resign, there would have to
be a general election within 30 days.
In
even more formal styles, we use were + subject-verb
inversion + to-infinitive:
[V]Were [S]we [to
-INF]to give up the fight now, it would
mean the end of democracy in our country. (If we gave up
the fight now …)
[V]Were [S]the
economy [to
-INF]to slow down too quickly, there
would be major problems. (If the economy slowed down too
quickly …)
As long as, so long as, providing, etc.
Sometimes
we need to impose specific conditions or set limits on a situation.
In these cases, conditional clauses can begin with phrases such
as as long as, so long as, only if, on condition that,
providing (that),provided (that).
As
long as is more common in speaking; so long
as and on condition thatare more formal and
more common in writing:
[to
a group of children]
You
can play in the living room as long as you don’t
make a mess.
So
long as a tiger stands still, it is invisible in the
jungle.
The
bank lent the company 100,000 pounds on condition that they
repaid the money within six months.
Providing
(that) is more common in speaking; provided (that)
is more formal and more common in written language:
[talking
about rail travel in the UK]
You
can get a senior citizen’s reduction providing you’ve
got a railcard.
They
may do whatever they like provided that it is
within the law.
See
also:
Or and otherwise
We
often use or and otherwise with
conditional meanings:
You’ve
got to start studying, or you’ll
fail all those exams. (If you don’t start studying, you
will fail the exams.)
[talking
about sending a package by mail]
We’d
better send it express, otherwise it’ll
take days. (If we do not send it express, it will take
days.)
Supposing
Supposing may
be used with a conditional meaning. It can be used in first, second
or third conditional sentences. The speaker invites the listener to
imagine a situation:
Supposing I
don’t arrive till after midnight, will the guest-house still be
open? (Imagine if I don’t arrive till after midnight …)
Supposing you
lost your passport, you’d have to go to the embassy, wouldn’t
you?
Supposing he
hadn’t recognised us – he might never have spoken to us.
See
also:
(“Conditionals:
other expressions ( unless, should, as long as )” from English
Grammar Today © Cambridge University Press.)
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