動詞 give off:

1. have as a by-product
2. give off, send forth, or discharge; as of light, heat, or radiation, vapor, etc.
   同義詞：emit, give out

1. Physicists are studying new ways of generating electricity with less damage to the environment. In the meantime, many power plants are being modernized to give off less polluting material.
   物理學(xué)家們正在研究對環(huán)境危害少的發(fā)電新方法，與此同時(shí)，許多發(fā)電廠也在實(shí)現(xiàn)現(xiàn)代化以減少污染物質(zhì)的釋放量。
2. As motor vehicles burn fuel, they give off carbon monoxide as a waste.
   在汽車燃燒燃料時(shí)，產(chǎn)生廢氣—一氧化碳。
3. When wine is fermented it gives off bubbles of gas.
   酒發(fā)酵時(shí)會放出氣泡。
4. All the radioactive materials give off the harmful radioactive which can be deadly at high levels.
   所有這些放射性材料都放出有害的射線，小則致癌，大能致死。