adverb
1
BAD : The accident happened at ten years ago.
GOOD : The accident happened ten years ago.
BAD : I came to England in two years ago.
GOOD : I came to England two years ago.
BAD : He went to Sydney before five years ago.
GOOD : He went to Sydney five years ago.
BAD : I started learning English since two years ago.
GOOD : I started learning English two years ago.
2
BAD : I'm writing in reply to your letter that I've received two days ago.
GOOD : I'm writing in reply to your letter that I received two days ago.
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With references to past time such as yesterday, last week, a year ago , use a past tense (NOT the present perfect): 'I came to England exactly six months ago.' (NOT 'have come')
3
BAD : The train left at exactly 3 o'clock. Just five minutes ago I had been stuck in a traffic jam.
GOOD : The train left at exactly 3 o'clock. Just five minutes before I had been stuck in a traffic jam.
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See note at BEFORE 1 (↑ before )