汽车和工厂烟囱所排出的烟是有毒的。

Fumes from automobiles and factory chimneys are toxic.

youdao

汽车排出的烟是造成烟雾的主要原因之一。

Automobile exhaust fumes are one of the major caueses of smog.

youdao

柴油机在起动后的暖机过程中排出大量含有未燃碳氢(HC)的蓝烟，给人类健康和社会环境都带来极大的危害。

When direct injection diesel engines are warmed up after running from cold start, they will emit a lot of blue smoke containing unburned hydrocarbons (HC) which are harmful to people and environment.

youdao