formed or forming

[abre]

HI, 👋

The Atlantic Ocean, formed when Europe split away from America 130 million years ago and that is still expanding today, will be Earth's largest ocean at some point in the distant future.

Should i use formed or forming. Because the sentence between comma is served as modifiers so there should be no verd. Then the AC forms, it shoud be forming instead of formed ,because it isn’t passive time. and some may say it should be formed because past participle should be used when thing happens in the past. so it is a matter of passive verb or past participle?

Another question is that , the use of that of , should i use that of or which, if i use which , should i use two which ? eg which forming/ forming....and which expending...

Much appreciated

 

[Uncle Jack]

Definitely use "formed". It is both in the past and it is passive: The Atlantic Ocean was formed when Europe split away from America. Admittedly, you could have "The Atlantic Ocean" as the subject of "form" in the active voice (The Atlantic Ocean formed when Europe split away from America), but the contrast between forming in the past and still expanding today means that you really want a past participle.

I also suggest you delete "that is"; you did not use "that was formed" so don't use "that is expanding". Use two participle phrases or two relative clauses, but mixing a relative clause with a participle phrase sounds awkward.

 

[abre]

So If it is only form without expand for contrast. Then what should I choose between active voice (forming)and past participle for past time(formed)?

 

[Uncle Jack]

So If it is only form without expand for contrast. Then what should I choose between active voice (forming)and past participle for past time(formed)?

I have very little idea what general rules there may be, but I think for an action in the past you need either a past participle ("formed") or a perfect participle ("having formed") and for an action in the present you need a present participle ("forming") or a passive present participle ("being formed"). These terms, particularly "passive present participle" might not be standard, but I don't know what the correct terminology is.

Where the noun is the agent of the action, then use a perfect participle or a present participle, but I am not sure that the converse is true, that when the noun isn't the agent that you have to use a past participle or a passive present participle. The Atlantic Ocean is not the agent of "form", and this remains true even when it is the subject of the verb in the active voice.

 

[abre]

Thanks!