What is a natural disaster? (自然災害 Zìrán zāihài)
typhoon, earthquake...
What is this?
This is a flood.
What is this?
This is a typhoon.
...
greenhouse effect (溫室效應 Wēnshì xiàoyìng)
What is this?
Global warming (全球暖化 Quánqiú nuǎn huà)
What causes the greenhouse effect?
smoke from factories
What causes the greenhouse effect?
smoke from cars