Question

spot the eror copper is an useful metal
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Answer 1

The answer is: Copper is a useful metal. "A" is used for words which begins with a consonant sounds and "An" is used for words which begins with a vowel sound like a,e,i,o,u. Using "A" or "AN" depends upon the sound rather than its spelling.

Answer 2

Answer:

Copper is a useful metal. 'A' is used even though useful starts with vowel because the sound is a consonant sound, there is a 'y' sound when we pronounce useful. We use 'a' when a word starts with a consonant letter and 'an' when it starts with a vowel.