adjective
1
BAD : It was a very interested idea.
GOOD : It was a very interesting idea.
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See note at BORING (↑ boring )
2
BAD : She is interested on learning French.
GOOD : She is interested in learning French.
BAD : I am not really interested by the job.
GOOD : I am not really interested in the job.
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interested in ( doing ) sth (NOT on/by/about ): 'I didn't know that you were interested in yoga.' 'The only thing she is interested in is having a good time.'
3
BAD : At school I wasn't interested to learn English.
GOOD : At school I wasn't interested in learning English.
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Use be interested to hear/read/know etc when you are talking about news or information: 'We were interested to learn that the research has been completed.' 'I'd be interested to know what you think of the idea.'
Use be interested in doing sth when you are talking about someone who wants to do something: 'She's interested in setting up her own business.'