verb
1
BAD : This policy is supposed to stop people to buy foreign cars.
GOOD : This policy is supposed to stop people from buying foreign cars.
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stop sb/sth (from) doing sth (NOT to do ), = prevent someone (from) doing something or something from happening: 'Her parents tried to stop her from going abroad.'
2
BAD : The child couldn't stop from talking.
GOOD : The child couldn't stop talking.
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stop doing sth (WITHOUT from ) = cease an activity: 'It's actually stopped raining at last.'
Compare: 'The rain stopped us from going out.'
3
BAD : I stopped to play the piano at the age of eight.
GOOD : I stopped playing the piano at the age of eight.
BAD : He loved toys and couldn't stop to look at them.
GOOD : He loved toys and couldn't stop looking at them.
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stop doing sth = cease or discontinue an activity: 'I stopped reading and turned out the light.'
stop to do sth = halt or pause (in order to do something): 'Although I was in a hurry, I stopped to talk to him.'