An airplane is a vehicle with wings and one or more engines that enable it to fly through

the air
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In this sentence, what does 'it' refer to? Does 'it' refer to 'an airplane' or 'a device'?

I'd say device.

It's a device with wings and engines.

The whole mechanism is called an airplane.

An airplane is a vehicle with wings and one or more engines that enable itself to fly through the air

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Thank you for your help. If 'it' refers to 'a device', don't we use 'itself'?

To determine what 'it' refers to in the sentence, we need to consider the context. In this case, 'it' most likely refers to 'an airplane' because the statement is describing the features and capabilities of an airplane. The word 'device' is not mentioned in the sentence, so we can disregard it as a possible referent for 'it'. Therefore, in this sentence, 'it' refers to 'an airplane'.