`1` Samuel has kept a diary since `1997.`
`2` We have learned English for fìve years.
`3` I have lived in Ho Chi Minh City since I was `8.`
`4` She started teaching the children in this remote village five months ago.
`5` The last time he wrote to me was in April.
`6` She last swam five years ago.
`7` They haven't talked to each other for two months.
`8` She hasn’t seen her elder sister since `1999.`
`9` It’s years since she last wrote to me.
`10` It’s ten years since Robert and Catherine got married.
S + HTHT (phủ định) + for + thời gian.
`to` It’s + thời gian ….+ since …+ last + QKĐ (khẳng định).
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S + HTHT (phủ định) + before.
`to` It’s + the first time + S + HTHT (khẳng định).
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S + HTHT (phủ định) + since / for + …..
`to` S + last + QKĐ (khẳng định) …+ when + mệnh đề.
`to` The last time + S + QKĐ (khẳng định) + was + thời gian.
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S + HTHT (khẳng định) + for + thời gian.
`to` S + began / started + V-ing + thời gian + ago.