A friend tells you that……如何回答?

英文原意是"有朋友告诉你说,吸烟应完全被禁止.要你礼貌地表示不同意见并说明理由."明白了句子的原意后,你可以按照你的想法和见解来回答这个问题,这不涉及中、英文问题,有了(中文的)见解,再用英文表述即可.
“hly2004”给出的三个理由不错,纠正一些小问题即可：
1）Sorry,I don't quite agree with you.(或：I'm afraid I don't really think so.)
2) First of all smoking is not as harmful as many people believe.
3) Secondly,it's not one day's effort.We should not ban it altogether,but should take a step by step approach .
4) Last of all,the cigarette industry provides many revenues as well as job opportunities.