1. 'Each' is used when there are two objects; here 'every' is not used.
In case there are more than two objects, either of the two may be used.
2. 'Each' can be used as a pronoun, but 'every' cannot. Note the difference between the following sentences:
Clearly, 'each' replaces the noun 'student'. 'Every' does not; it requires to be followed by the noun, or by 'one of them'.
3. With adverbs (practically, nearly, almost, etc), only 'every' is used. In the following sentences, 'every' cannot be replaced by 'each':
4. 'Every' is used to refer to repeated, regular events, as in the following cases:
In the above examples and any similar instances, 'each' cannot be used.
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