假定你是李华，你们学校在3月22日"世界水日"来临之际将举办一系列活动。请写一封邮件给学校英语外教Mr.Green，请他为本校学生开设讲座。邮件的内容包括：
1.讲座主题：废水处理与利用；
2.讲座目的；
3.讲座时间及时长。
注意：
1.词数80左右；
2.可以适当增加细节，以使行文连贯；
3.开头和结尾已给出，不计入总词数。
Dear Mr.Green，
________________
Yours，
Li Hua

【考点】提纲作文．

【答案】Dear Mr.Green，
    With World Water Day around the comer，our school is planning to hold a series of activities.I'm writing to invite you to give us a lecture on the topic of wastewater disposal and utilization.
    The lecture will be held in our school hall from 4：00 to 5：30 on the afternoon of March 22.We hope it can arouse students' awareness of water crisis as well as develop the habit of water recycling.If everyone can make good use of water，we together can make a big difference.
    I would be grateful if you could accept my invitation.
Yours，
Li Hua