`1.`The last time Lucy wore that dress was Barbara's wedding.

`→`Phủ định của hiện tại hoàn thành : S + have/has not + VPII + for/since thời gian

`=`The last time + S last + V quá khứ + was + time + ago

`2.`My sister began studying French 2 years ago.

`→`S + have/has + VPII + for/since + thời gian

`=`S + started/began + Ving/To V + thời gian

`3.`It's the first time I have ever seen such a mess.

`→`S + have/has never + VpII (before)

`=`It/This is the first time + S + have/has (ever) + VpII

`4.`It's 4 years since Robert and Catherine got married.

`→`S + have/has + VPII + for/since + thời gian

`=`It’s + time + since + S + last + V2/ed + O

`5.`How long have Catherine and Henry been engaged ?

`→`When + did + S + V nguyên mẫu ?

`=`How long + have/has + S + VpII ?

or How long is it since + S + V quá khứ ?

1. THe last time Lucy wore that dress was at Babara's wedding. (S+has/have+P2/ed+O+since+time -> The last time+S+V2/ed+was+at+time)
2. My sister began studying French 2 years ago. (S+have/has+V3/ed+O+for+time -> S+began+V-ing+O+time+ago)

3. It's the first time I have seen such a mess in my life. (have ner seen = It's the first time I have seen...)

4. It's 4 years since Robert and Catherine married. (S+have/has+P2/ed+for+time -> It's+time+since+S+V2/ed)

5. How long have Catherine and Henry got engaged? (When+QKĐ->How long+HTHT)