`1.` Jack is having a video conference with his colleagues in Asia at the moment

`-` at the moment`-` HTTD

`-` HTTD: `(+)` S + am/is/are + V_ing + O

`2.` He said that he was doing well in science at school then

`-` Câu gián tiếp:
S + said + (that) + S + V(lùi thì)

`-` lùi thì: HTTD `-` QKTD

`-` now `-` then

`3.` Nick asked the professor why homans couldn't live on Mars

`-` Câu gián tiếp dạng Wh_question:
S + asked + O + Wh_ + S + V(lùi thì)

`-` can `-` could

`4.` Robots will replace human in 30 years'time 

`-` TLĐ: `(+)` S + will + V_inf + O

`5.` Many students asked me what differences Mars and Earth were

`-` lùi thì: HTĐ `-` QKĐ