`3)` When did she live in Ha Noi?

`->` Wh- + did + S + V-inf ... ?

`4)` It has been `20` years since I last came to the countryside.

`->` It has been years since S + last + V-ed: đã bảo lâu kể từ khi ai làm gì

`5)` This is the first time Tom has ever learnt Spanish.

`->` this is the first time S have/has + ever+ V3: lần đầu ai làm gì

`6)` How long is it since they played soccer?

`->` How long is it been since S last V-ed?: đã bao lâu kể từ lần cuối ai làm gì

`7)` He has never swum in the river before.

`->` S + have/has + never + V3 ... before : ai chưa từng làm gì trước đây

@magnetic

`3,` When did she start living in Hanoi? 

`@` How long+has/have+S+V-pp+O?: Ai đó đã làm gì đó được bao lâu rồi?

`=` When+did+S+start/begin + V-ing+O?: Ai đó đã bắt đầu làm gì từ khi nào?

`4,` It has been `20` years since I last came to the countryside. 

`@` S+has/have+not + V-pp+O+ for+ khoảng thời gian. 

`=` It has been + khoảng thgian + since+S+last+V2/V-ed+O. 

`5,` This is the first time Tom has learnt Spanish.

`@` S+has/have+never+V-pp+O+before.

`=` This is the first time +S+has/have+V-pp+O.

`6,` How long is it since they played soccer?

`@` When did+S+ V-bare inf+O?

`=` How long is it/ has it been + since+S+ V2/V-ed+O?

`7,` He has never swum in the river before.

`@` This is the first time +S+has/have+V-pp+O.

`=` S+has/have+never+V-pp+O+before.