If there are two sentences given to me:
- I can't do it. (Can't + simple verb)
- It can't be changed now. (Can't + be + past verb)
I'm not able to tell the difference in use. When do we use 1) or 2) ?
I took 2) from my book by the way, here's the full context:
You've signed the contract. It can't be changed now.
and I'm still confused, why don't we use simple verb like: it can't change now?
I can't do it is a sentence in the active voice. There is a thing that I cannot do.
It can't be changed is a sentence in the passive voice. There is a thing that cannot be done to [an object].
Looking up "Active vs passive" will help you understand which one you should use when. In general, the active voice is used when you want to emphasize the person or thing doing the action, and the passive voice is used when you want to emphasize the action itself.
It would not be correct to use You've signed the contract. It can't change now. This is because the contract is an inanimate object; it could never change (itself). Instead, some person has to change the contract by crossing words out and writing new ones. It can't be changed now is the proper way of expressing the thought that the contract is set and unmodifiable. Another way to say it would be You can't change it now, but that leaves open the possibility that someone else might be able to change it; the original sentence means no one is able to change it.
