adjective
BAD : Drugs are responsible of a large number of deaths.
GOOD : Drugs are responsible for a large number of deaths.
BAD : I'm also responsible to decide on the best way to manufacture a product.
GOOD : I'm also responsible for deciding on the best way to manufacture a product.
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responsible for (doing) sth : 'Who's responsible for roof repairs - you or the landlord?' 'The person responsible for leaking the story to the press has been forced to resign.'