Conditionals

• A conditional sentence consists of the main clause and the conditional clause.
  
• In conditional sentences, the conditional clause starts with if or with other conditional link words:
  unless (wenn, es sei denn, außer dass), 
  as/so long as (so lange, bis zu), 
  suppose/supposing [that] (angenommen, vermutend),
  providing/provided [that] (vorausgesetzt, insofern), 
  on condition [that] (unter der Auflage/Bedingung [, dass])
  in case (sofern, falls), 
  when (wenn, sobald),
  etc.

Type 0:  Conditions which are always true

• If it rains, the ground becomes wet.
• When you put salt on ice, it melts.
• If you see her, give her my love.

Type 1:  Conditions which are very probable in the present or future

• If you live in Britain, you will know all about the bad weather.
  Present Simple / Future
• If you have lived in Britain, you will know all about the bad weather.
  Present Perfect / Future
• If you are living in Britain, you will know all about the bad weather.
  Present Continues / Future
• As long as you bring it back on the dot of six, you can borrow my car.
  Present Simple / can
• If you're hoping to get there for the start, leave now.
  Present Continues / Imperative 
  

Type 1 with should:  Conditions which are less likely

• If you should need any help, just let me know.

Type 1, Inversion with should:  For very formal situations

• Should you need any help, please don't hesitate to contact me.

Type 2:  Conditions which are impossible or improbable in the present or future

• If we had more confidence in our memories, we would remember more.
  

Type 2 with were:  For formal situations

• If we were to accept your conditions, would you be prepared to increase the loan?

Type 2, Inversion with were:  For very formal situations

• Were we to increase the loan, would you guarantee repayment?

Type 3:  Unreal conditions in the past

• If the telephone hadn't woken me, I'd have been late for my appointment.
• She could have gone to university if she'd wanted to.

Mixed:   Unreal conditions in the past   with a unreal present or future result

• If I had driven faster, we could be there now.
• If she hadn't decided to change jobs, she would be going to China next month.
  

Mixed:   Unreal conditions in the present (past)   with a unreal past result

• If I spoke Japanese, I might have got that job.
• If I didn't trust him, I wouldn't have let him look after the baby.