202 Useful Exercises for IELTS Side1-24-Ex3.8Dictation1（在线收听）

       Narrator: Exercise 3.8. Dictation 1:

　　Air pollution / is probably the modern world's greatest threat. / Water can be filtered, / land can be cleared, / but filthy air can only be filtered / by the nose and lungs. / It is estimated / that living in a big city / is equivalentto smoking / half a packet of cigarettes a day. / What is more, / the most dangerous components of air pollution/ are invisible gases. / We cannot smell or see / the dangerous gases given off / from the exhausts / of cars, lorriesand buses. / However, / this does not mean / they are not present in our bloodstream / every time we take a breath.
　　/ It is obvious / that our future health / depends on the development / of a safer vehicle engine.