$\color{#788AB2}{Ma}$$\color{#93A0C6}{ri}$$\color{#B3C1DC}{i}$

`11.` We have not celebrated her birthday for three years.

The last time + S + V2/ed + was + thời gian.

= S + have/has + not + V3/ed + for + khoảng thời gian.

`12.` Is this your first time at a live concert?

Have you ever + V3/ed + before?

= Is this the first time + S + have/has + V3/ed?

`13.` They have not launched a new product for almost a year.

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

= S + have/has not + V3/ed + for + khoảng thời gian.

`14.` It's been a long time since I attended a music festival.

S + have/has not + V3/ed + since + mốc thời gian.
= It's been + khoảng thời gian + since + S + V2/ed

`15.` We have not met since John's wedding.

The last time + S + V2/ed + was + mốc thời gian.

= S + have/has not + V3/ed + since + mốc thời gian.