`1`. It's good for us to keep our traditional customs 

`=>` We should keep our traditional customs

⇒ Cấu trúc: S + should/ shouldn't + Vo + O

⇒ should + Vo

`2`. They built that house two years ago

`=>` They have built that house for two years

⇒ Cấu trúc: S + have/has + V3/-ed + O

⇒ They là danh từ số nhiều `->` Dùng have

⇒ for + khoảng thời gian

$1.$ It's good for us to keep our traditional customs
$→$ We should keep our traditional customs.

It + be + good + for + somebody + to + V_nguyên thể.

S + should + V_nguyên thể.
$2.$ They built that house two years ago
$→$ They have built that house for two years ago.

S + have/has + V3 + for + khoảng thời gian/since + thời gian được xác định.

$#Mei UwU$