Pairwork is a very important part of being in an English class, but it doesn't always work out well. Here are some ways to make sure you get the most out of it.
Speakers from your home county - This is the only one where you can do something about it very easily. If you are in a mixed class, you can request to your teacher that you are with someone who is not from your own country. If you are Japanese, and with another Japanese student then you will probably not be able to recognise each others' errors at all. If you ask the teacher privately then they will usually just say "okay everyone, let's move around a bit, it's good to change things around sometimes", and then you will definitely be with someone else
Quiet partners - Not everyone is an extrovert. So to get the most out of this situation you need to develop a good relationship with your partner so that they feel comfortable talking. You need to be patient because they will often take a longer time to get started, and will finish quickly. You can ask some extra questions even though they aren't expected or in the task. You can usually ask 'why' or, 'how about an example' if their answer is very short.
Finishing too quickly - Many students think of the activities as a race. If an interesting topic comes up, then you can follow the topic for a little while. If your partner activity is to talk about experiences from the past 'have you ever....?', and your partner has done something quite amazing, you can get some more information and expand on it.
A: Have you ever lived overseas?
B: Yes, I have.
A: Have you ever eaten raw fish?
B: No, I haven't.
If the discussion is like this then it will be over too quickly. If they have done something, then you can ask 'when'? Everyone else will still be talking, if you find that you are generally finishing early, then just find some ways to extend it. If you feel that you never finish you can try to move a little faster, but if you aren't finishing it is probably because the teacher isn't giving you enough time - you need 5 - 10 minutes to get through most speaking activities in a textbook.