2. "Have humans been able to communicate with people on other planets?" 

=> Samuel asked the scientist___________to communicate with people on other planets

3. "Did the Roswell UFO incident take place in the U.S in June 1947?" 

=> Nick asked the journalist_______the Roswell UFO incident________in the US in June 1947

`2.` Samuel asked the scientist if/whether humans had been able to communicate with people on other planets.

`-` Lùi thì: HTHT `->` QKHT (S + had + Vpp)

`-` tobe able + to V: có khả năng làm gì

`3.` Nick asked the journalist if/whether the Roswell UFO incident had taken place in the US in June 1947.

`-` Lùi thì: HTHT `->` QKHT (S + had + Vpp)

`***` Câu tường thuật với câu hỏi Yes/No:

S + asked (sb)/wanted to know/wondered + if/whether + S + V (lùi thì)

`color{aqua}{\text{_ThuyLinh}}`

`2,` Samuel asked the scientists if humans had been able to communicate with people on other planets.

- Lùi thì : HTHT -> QKHT

- be able to do sth : có thể làm được điều gì đó

`3,` Nick asked the journalist if the Roswell UFO incident had taken place in the US in June 1947.

- Lùi thì : HTHT -> QKHT

- take place (phr.v) : diễn ra

- Câu tường thuật dạng Yes/no Questions : S + asked (O)/wondered/wanted to know + if/whether + S + V(lùi thì) + O