16 She asked if I often did my homework after school

17 He said he had gone to the library the day before

18 The police asked where I had stayed the night before

19 The girl said she was going on holiday the day after

20 They said they were going to learn E then

21 She told me she was going away for a few days and would phone me when she got back

`16.` She asked me if I often did my homework after school

`17.` He said that he had gone to the library the day before

`18.` The police asked me where I had stayed the night before

`19.` The girl said that she was going on holiday the next day

`20.` They said that they were going learning Enghlish then

*Statement:

S + said + (that) + S + V

S + said + to + O + (that) + S + V

S + told + O + (that) + S + V

*Yes - No question: S + asked + (O) + if/ whether + S + V

*Wh - question: S asked + (O) + question word + S + V

*Lùi thì:

QKĐ → QKHT

HTĐ → QKĐ

HTHT → QKHT

HTTD → QKTD

QKTD → QKHTTD

HTHTTD → QKHTTD

will → would

can → could

may → might 

must → had to

shall → should

be going to → was/ were going to