`1` astronauts worked .

`-` work `->` worked .

`2`  she could fly .

`-` can `->` could .

`3` scientists could discover .

`-` can `->` could .

`4` aliens would be .

`-` will `->` would .

`5` tourists could travel .

`-` can `->` could .

`6` there were .

`-` are `->` were .

`7` they needed .

`-` need `->` needed .

`8` the Milky Way was `-` included .

`-` is `->` was .

`-` includes `->` included .

`9` were .

`-` are `->` were .

`10` could exist .

`-` can `->` could .

`-----` 

`+` Cấu trúc câu gián tường thuật .

`@` S + said/told + O + that + S + V(lùi thì) + O .

`+` Cấu trúc câu hỏi ''Wh-question'' .

`@` S + asked + O + Wh-question + S + V(lùi thì) + O .