1.I last met my teacher three years ago

$\Rightarrow$ It’s been three years since I last met my teacher.

2. " Don't keep silent if you don't understand, Lan" said the teacher

$\Rightarrow$ The teacher told Lan not to keep silent if she didn’t understand.

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$-$ Cấu trúc: “It’s been…since…” (tương tự nhưng diễn đạt theo cách khác)

$-$ Cấu trúc: “The teacher told…” (cùng một ý nghĩa nhưng theo dạng trực tiếp)

1. It's been three years since I last met my teacher.

- It's been + khoảng thời gian + since + S + last + V2/ed

2. The teacher told Lan not to keep silent when she didn't understand.

- S + told + O + (not) to V: bảo ai (không) làm gì