5: Since the appearance of electronic devices, lessons have become more and more enjoyable and effective.
6: Do you think there would be less conflict in the world if all people spoke the same language?
7: Deforestation will lead to the extinction of rare animals due to the loss of their habitats, and extreme floods and land erosion.
8: The Vietnamese government has done a lot to eliminate hunger and poverty.
9: Global warming has had negative impact on our environment.