27. She was my best friend, but we arent friends any more. (used to) . 28. My uncle was a bus driver when he was young. (used to) . 29. I liked watching cartoons when I was a kid. (used to) . 30. When I was small, I cried a lot. (used to) .

`answer`:

`27`. She used to be my best friend, but we aren't friends anymore.

`28`. My uncle used to be a bus driver when he was young.

`29`. I used to like watching cartoons when I was a kid.

`30`. When I was small, I used to cry a lot.

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`(+)` S + used to + V(inf - nguyên thể) : diễn tả một thói quen, một hành động thường xuyên xảy ra trong quá khứ mà bây giờ không còn nữa