8.140 omitting words in the second clause

When you link clauses which have the same subject, you do not always need to repeat the subject in the second clause.

If the conjunction is 'and', 'or', or 'then', you do not usually repeat the subject.

If the conjunction is 'but', 'so', or 'yet', it is usual to repeat the subject.

When you link clauses which have different subjects but which have some common elements, you do not need to repeat all the elements in the second clause.

For example, instead of saying 'Some of them went to one pub and some of them went to the other pub', you can say 'Some of them went to one pub and some to the other'.