计算:(2x-1)2-2(x-2)(x+6).
解;原式=4x2-4x+1-2(x2+4x-12)=4x2-4x+1-2x2-8x+24=2x2-12x+25.
. He was late for the meeting because the bus he took ______ halfway.
A.broke in
B.broke down
C.broke out
D.broke up
现在,很多中学生每天长时间用耳机听音乐、学英语。你的英语笔友李平也是如此。最近他在来信中提到感觉头痛、注意力不集中、记忆力减退。请你就此回信谈谈你的观点和建议。
写作要点:
1.简述过度使用耳机的现象;
2.分析过度使用耳机的危害;(至少两点)
3.提出你的建议。(至少两条)
注意:
1.要点齐全,可适当添加细节,以使行文连贯;
2.字数120左右。开头和结尾已给出,不计入总词数。
3.可能用到的词汇:耳机earphone
Dear Li Ping,
I received your letter yesterday...
____________________________________________________________________________________________
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Best wishes.
Yours,
Lin Tao