Flyer 1 flew(3.5meter) high(对括号部分提问)

问题描述:

Flyer 1 flew(3.5meter) high(对括号部分提问)
2.Air pollution comes from smoke and bust (from power stations)(对括号部分提问)
3.The smell of flowers is sweet(保持原意)

where the smoke and bust that cause air pollution come from.
the flowers smell sweet.