1, B ->had told.
2, A -> Because of.(because of + noun/V-ing)
3, A -> which.
4, D -> swallowing.
5, B -> was. (each of + N + V số ít)
6, B -> on.(to congratulate somebody on something/Ving: chúc mừng ai
7, B ->has. (neither/either of + N + V số ít)
8, B -> had been left.( câu bị động)
9, C -> five-speed.
10, D -> from selling.(to prevent somebody from doing something: Khiến ai không làm được gì )
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