Please explain to me "unless" and "if"

Dear teachers,
Please explain to me “unless” and “if”.
Please give an example for each.
Thanks

Hi mlngvt,

Unless has the sense of if not. Look at these sentences:

If you hurry, you’ll catch the train.

If you don’t hurry, you’ll miss the train.
Unless you hurry, you’ll miss the train.

Alan

Thanks teacher for your reply.
Please have a look at my practice:

  1. Is this sentence right if the word “up” will be omitted?
  2. Is this sentence wrong if the word “up” won’t be omitted?.
    I will replace sentence 2 like this:
  3. Is this sentence wrong unless the word “up” will be omitted?.

She still does the washing up by hand because she is too poor to buy a washing machine.

Thanks.

She still does the washing up by hand because she is too poor to buy a washing machine.

Personally, I use ‘washing’ for clothes and ‘washing up’ for dishes, but I wouldn’t say that your sentence is wrong.

Thanks Conchita for your correction. It’s very useful to me.
Is the original sentence or the sentence after omitting 'up" right?
Please make it clear. Thanks.

I suggest you write either:

She still does the washing up by hand because she is too poor to buy a dishwasher.

Or:

She still does the washing by hand because she is too poor to buy a washing machine.