45. You had to send that card today or you would have missed your mother's birthday.

- Have got + to V = Have to V: Bắt buộc làm gì.

- S + V + O + or + S + V

46. It's worth building a new playground for the children in the area.

- It + tobe + adj + to V: Thật như thế nào để làm gì

- Be worth V - ing: Đáng làm gì

47. He regretted not having said / not saying goodbye to her at the airport.

- Regret not having V3/ed  / not V - ing: Hối tiếc vì đã làm gì.

48. It's possible that we might use smart mirrors that allow us to try on virtual clothing in the future.

- It's possible + that + S + V: Điều đó là có khả thi khi ai đó làm gì.

- Allow sb to do sth: Cho phép ai làm gì.