`1.`The last time we were taken to the zoo was 5 months ago.

`2.`Tom hasn't come back to his hometown for 5 years.

`=>`Form : The last time + S + V2/ed + was + time ( Thời gian trong quá khứ )

`=`Phủ định của hiện tại hoàn thành : S + have/has not + Vpp + since/for + time

`=`It's + time + since + S ( last ) + V2/ed

`=`S + last + V2/ed + time 

`1` The last time we were taken to the zoo was 5 months ago 

`-` The last time + S + Ved/V2 + was + ... 

`-` S + has/have + not + Ved/V3 

`-` Câu bị động đối với thì Hiện Tại Hoàn Thành : has/have + been + Ved/V3

`2` Tom hasn't come back to his hometown for 5 years

`-` The last time + S + Ved/V2 + was + ... 

`-` S + has/have + not + Ved/V3 

`-` come - came - come