Teacher Discussion Forums

Sample sentence:
Every year ozone disappears from the Antarctic, creating a hole that is dangerous to life on Earth.

You could insert "which is" before the word creating, or leave it out. The meaning of the sentence is not lost.

My question is, is there a rule for omitting or requiring such wording as "which is"? I don't think it has to do with identifying vs. non-identifying clauses. I am wondering if it has to do with the verb form (in this instance present continuous "creating").

Follow-up question:
In the sample sentence below...

She cycled from London to Glasgow, which is pretty good for a woman of 75.

My intuition says you can leave out "which is", but it makes the sentence less formal/academic and more casual. Right or wrong?

There is a rule on that. If you have an grammar in use book, its unit 89 (got that question from my girlfriend not long ago so I remembered it). -ing clause can mean what a person or thins was doing something at a particular time "The woman TALKING TO TOM is fat." or a permanent characteristic not true at just one particular time "I live in a nice apartment overlooking the ocean."

I think the example of the cycling woman is only used in informal speech and writing and is not a grammatical rule. Could be wrong on that though.

She cycled from London to Glasgow - pretty good for a woman of 75.

The casual nature of that is because the second clause is verbless. You need a pause between the first and the second clause because 'which' is referring to the whole clause, and not to Glasgow.

I think you are putting it the wrong way when you refer to missing out 'which is'. In your first example there is no need for it to be there in the first place; a present participle can start an appositional clause.

She cycled from London to Glasgow, breaking the speed record for the over 70s.