`***` Bổ sung:

`-` I + am

`-` He/She/It/N số ít + is

`-` We/You/They/N số nhiều + are

`-------------`

`1.` is buying

`2.` isn't studying

`3.` Is she running

`4.` is eating

`-` DHNB: now

`5.` are you waiting

`6.` aren't trying

`7.` are having

`-` DHNB: right now

`8.` are travelling

`-` DHNB: now

`9.` is drinking

`10.` is speaking

`-` DHNB: Listen!

`11.` is getting

`12.` are staying

`-` DHNB: at the moment

`13.` is happening

`14.` is having

`15.` isn't

`-` DHNB: at present

`16.` aren't drinking

`-` DHNB: now

`17.` is composing

`-` DHNB: at present

`18.` are having

`-` DHNB: right now

`19.` am not drinking

`20.` is lying

`-` DHNB: now

`5.` are you waiting

`6.` are not trying

`7.`are having

`-` now `-` HTTD

`8.` are travelling

`-` now `-` HTTD

`9.` is drinking

`10.` is speaking

`-` listen! `-` HTTD

`11.` is getting

`12.` are staying

`13.` is happening

`14.` is having

`15.` is not 

`-` at present `-` HTTD

`16.` are not drinking

`-` now `-` HTTD

`17.` is composing

`18.` are having

`-` right now `-` HTTD

`19.` am not drinking

`20.` is lying

`-` Now `-` HTTD

`______________________`

`@` HTTD:

`(+)` S + am/is/are + V_ing + O

`(-)` S + am/is/are + not + V_ing + O

`(?)` Am/is/are + S +  V_ing + O?

`-` DHNB: now, today, right now, nowadays, at present, at the moment,...