Look at this sentence:

• If Winston Churchill was alive today, he would be over 100 years old.

Of course, Churchill isn’t alive today (he died in 1965). The sentence imagines something that is not true. The verb after if is Past Simple, but it actually refers to the present. This structure is called the Second Conditional:

Another example is someone who doesn’t have enough money to buy a new car and says:

• I’d buy a new car if I had enough money.

Note that we do not use a comma (,) after if.

We can use the same type of sentence to talk about the future:

The above sentence describes an unlikely future situation: it is unlikely that I will win such a lot of money.

We can use wish to say that we want something to be different from how it is now. Note that the verb after wish is past (e.g. could, was, had):

• I wish (that) my flat was bigger.
• Hugh wishes he could speak German.
• I wish I had a million pounds.

After wish and if, we sometimes use I/he/she/it with were:

• If he were (or was) still alive today, …
• I wish my flat were (or was) bigger.

Note also the expression if I were you, when you give somebody advice:

• If I were you, I’d talk to John. (NOT If I was you, …)