Can a ethereum smart contract look up the current dollar/ether exchange rate and then change its behaviour depending on it?? and how? [duplicate]

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• How can an Ethereum contract get data from a website? 5 answers

1. can a contract on blockchain get outside data like "current dollar/ether exchange rate" using api like call??
2. If yes, how can it be done? and is there any technique to control the behaviour of the contract depending on outside factors like fluctuations in ether/ dollar currency?