Page 493 - Practical English Usage 3ed - Michael Swan, Oxford

475
punctuation (3): semi-colon
instead of full stops
Semi-colons (i) are sometimes used instead of full stops, in cases where sentences are grammatically independent but the meaning is closely connected. Semi-colons are not nearly as common as full stops or commas.
Some people work best in the mornings; others do better in the evenings.
It is a fine idea; let us hope that it is going to work. Commas are not usually possible in cases like these (see 476).
in lists
Semi-colons can also be used to separate items in a list, particularly when these are grammatically complex.
You may use the sports facilities on condition that your subscription is paid regularly; that you arrange for all necessary cleaning to be carried out; that
you undertake to make good any damage; ... For commas in lists, see 476.
punctuation (4): comma
Commas (,) generally reflect pauses in speech. co-ordinate clauses
Clauses connected with and, but or or are usually separated by commas unless they are very short. Compare:
- Jane decided to try the home-made steak pie, and Andrew ordered Dover sale
with boiled potatoes.
Jane had pie and Andrew had fish.
- She had very little to live on, but she would never have dreamed of taking what was not hers.
She was poor but she was honest.
subordinate clauses
When subordinate clauses begin sentences, they are often followed by commas. Compare:
Ifyou are ever in London. come and see me.
Come and see me ifyou are ever in London. Commas are not used before that-clauses.
It is quite natural that you should want to meet your father. (NOT ..¥. is t{r:tife Ilttfflml, tlMt ...)
grammatically separate sentences: commas not used
We do not usually put commas between grammatically separate sentences (in places where a full stop or a semi-colon would be possible - see 473 and 475). The blue dress was warmer. On the other hand, the purple one was prettier. OR The blue dress was warmer; on the other hand ... (NOT The hlr:te aFes3
476
1
1
2
2
3
Wtf:S lHttrtner, BII the 6the, htlM . ....)
punctuation (4): comma 476
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