1. Alex hadn't done the gardening before it started raining. 

2. The amount of plastic in the ocean wil increase if we don't take action now.

3. Outdoor air pollution causes more than 3 million deaths a year.

4. There have been more than 80,000 wildfires so far this year.

5. What would you do if you caught in a hurricane’s path?

6. By the time Hurricane Gilbert hit Mexico it was changing characteristics.

7. Heavy rains lashed the coast of Orissa and Andhra Pradesh in 2013.

8. since early morning news , tornado warnings have issued for storms in Oklahoma.

9. Water pollution makes aquatic plants and animals died.

10. Survivors said that many people managed to escape, but they could not run away fast enough.

1.hadn't done

⇒ Cấu trúc: Before + QKĐ, QKHT

2.will increase... don't take.

⇒Dấu hiệu: now

⇒ Câu điều kiện loại 1: If S + don't/doesn't Vo, S +will/won't + Vo

3.caused

⇒ Ô nhiễm không khí ngoài trời đã gây ra hơn 3 triệu cái chết mỗi năm.

4.have been.

⇒ Dấu hiệu: so far

⇒ Thì HTHT

5.caught

⇒ Câu điều kiện loại 2: If S + V(QKĐ), S + would +Vo

6.hit... had changed

⇒ Cấu trúc: By the time + QKĐ, QKHT

7.lashed

⇒ Dấu hiệu: in 2013

⇒ thì QKĐ

8.have issued

⇒ Dấu hiệu: since

⇒ thì HTHT

9. die

⇒ Cấu trúc: make + O +adj

10.to escape

⇒ Công thức: manage + to V.

             CHÚC BẠN HỌC TỐT NHA!!!