`61.` It is the first time I have been to the ballet before.

Giải thích: $\text{It is the first time + (that) + S + have/has + Verb(pp)}$

`62.` It is twenty years since John and Mary last moved to Edinburgh.

Giải thích: $\text{ It is...since S + Ved/V2}$

`63.` For two months now the police have been looking for him.

Giải thích: $\text{S + have been + V-ing + ...}$

`64.` This is the first time I have seen a dirtier-looking dog.

Giải thích: $\text{This is the first time + S + have/has + P2}$

$\text{S +have/has + (never) + P2 + before}$

`65.` It is hours since Mary last rang.

Giải thích: $\text{ It is...since S + Ved/V2}$

`66.` Alan hasn't visited his parents for ages.

Giải thích: $\text{S + have/has(not) + Ved/V3 + ...}$

`67.` It is 8 years since she last started to learn English.

Giải thích: $\text{ It is...since S + Ved/V2}$

`68.` It is the most beautiful building I have ever seen.

Giải thích: $\text{S + have/has(not) + Ved/V3 + ...}$

`69.` This is the most romantic story I've read.

Giải thích: $\text{This + be + superlative adj + N + S + have + ever + P2}$

`70.` It was the coldest winter they had ever had

Giải thích: $\text{It was + the superlative adj + N + S + had + ever + + P2}$

`71.` Mr. Jones is the most dangerous person you wiIl ever meet.

Giải thích: $\text{S + be + the superlative adj + N + S + ...}$

$chucbanhoctot$

$#thaonguyeneakar$