成人高考英语作文题目是：你（LiYuan）的班级即将组织一次交友（picnin），请你给你的外籍老师（Steve）写封信。
一、作文内容包括：
（1）邀请他参加此次活动；
（2）介绍活动的具体安排和内容（如时间，地点等）；
（3）告知需要做的准备（如着装，自备午餐等）；
（4）希望他参加并尽快给予答复。
二、英语作文范文：
MynameisLiHua.Ihavethehonorofbeingyourguide.I'dliketogiveyouabriefintroductiontoourfieldtriptoday.
First,we'llstartat8:30fromschoolgettothefootofthemountainatabout9:00.Thenwe'lltheclimbthemountain.It'lltakeaboutonehourtoreachthetopwherestsometemples.Wearefreetolookaroundthetemplesfrom10:00to12:00.Besides,we'llhavelunchthere.Afterashortbreak,we'llgodowntheothersideofthemountainat2:00pm.Weplantoreachtheriversideatabout3:00pm.We'llgoontoourtripdowntheriverbyboatenjoythescenery.Finallywe'llbebackatschoolatabout5:00pm.
That'sallfortoday'sarrangement.Iwishyouallawonderfulday.Thanks.
ApicnicwillbeheldinthisSundayat7:00a.m.intheBeiHaiPark.
Wewillgototheparkbybusat6:00a.m.,sodontbelate.Wewillenjoysomeshowsprovidedbyourstudentsinthemorning.intheafternoon,wewilldosomegamestoenjoyus.
Thankyouforcooperation!
LiYuan