1. Is Eric walking?

$-$ No, he isn't. He is climbing.

2. Are Kamian and George cycling?

$-$ No, they aren't. They are playing tennis.

3. Is Helen playing tennis?

$-$ No, she isn't. She is cycling.

4. Is Alan swimming? 

$-$ No, he isn't. He is surfing.

5. Are Louise and Mike walking?

$-$ Yes, they are.

6. Is Sita climbing?

$-$ No, she isn't. She is running.

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$×$ Cấu trúc thì HTTD:

$(+)$ S + is/am/are + V_ing.

$(-)$ S + is/am/are + not + V_ing.

$(?)$ Is/Am/Are + S + V_ing?

⇒ Yes, S + is/am/are. 

⇒ No, S + is/am/are + not.

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$@haanx2$