`50.` Let's collect unused clothes.

`-` Let's + V-inf: Hãy ...

`=` S + suggest + V-ing: đề nghị

`51.` She failed in the exam because of her laziness.

`-` because of + N/N.P/V-ing: bởi vì

`52.` Ba is tired because he stayed up late watching TV.

`-` because + clause: bởi vì

`53.` Since Hoa was careless, she broke the cup.

`-` Since + clause: bởi vì

`54.` We were disappointed that she didn't keep her promise.

`-` be disappointed that + clause: thất vọng rằng _____

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`50` Let's collect unused clothes.

`-` Let's + V

`51` She failed in the exam because of her laziness.

`-` S + V + because of + N/Ving: bởi vì

`52` Ba is tired because he stayed up late watching TV.

`-` S + V + because + S + V: bởi vì

`53` Hoa broke the cup since she was careless.

`-` S + V + since + S + V: bởi vì

`-` since `=` because `=` as: bởi vì

`54` We were disappointed that she didn't keep her promise.

`-` S + be + adj + that + S + V