$\text{Ánh Vânn}$

`44`. B

`45`. C

`46`. C

`47`. We really enjoyed the fireworks display on New Year's Eve last year.

`48` . Scientists are thinking about how to use the rise and fall of the tide to produce electricity.

`49`. Minh wishes he could speak English as fluently as a native speaker.

`50`. We have not seen Martin since we left college.

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Quá khứ đơn

`@` S + V-ed +....

`@` S + didn't + V-inf

`@` Did + S + V-inf...?

DHNB: Last month,year, yesterday,...

`***` S + haven't/hasn't + seen + since/for: Đã bao lâu không nhìn thấy ai

`->` Enjoy: Thích thú, tham gia vào điều gì

`-` So sánh nhất

`+` Tính từ ngắn

`***` S + tobe + the + adj-est

`+` Tính từ dài

`***` S + tobe + the most + adj