更正在括号处注明!总共十处错误.
As we all konw (去掉it),smoking is very harmful to our health.For us teenagers it does (great) harm not only to our health but also to our mind.Now more and more (people) begin to realize its harm.Many people over the world (have) given up smoking.(But) some middle school students have formed (a) bad habit of smoking.It's bad for their health and study.We middle school students are the future (builders) of our country.We should work (去掉more) hard and learn something useful for our country,the people and ourselves,(too).It's time for (us) get rid of the bad habit of smoking.