增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：1）每处错误及其修改均仅限一词；

2）只允许修改10处，多者（从第11处起）不计分。

Dear Tom,

    I have heard that you were to come to our school as an exchange student. I, on the behalf of our class, welcome you warm. Now, I'd like to introduce some details about our class.

    Our class is a very warm family. There are 50 students in our class, included 30 boys and 20 girls. You will find easy to join us since we all want to make friends with you. Whenever you get in trouble, you are ready to lend our hand to you. At last, I personally advice you to learn some basic Chinese to communicate with locally people. It is much easier for you to get on to teachers and classmates by speaking Chinese.

    Yours,

    Li Hua

①除了细胞之间形成通道外，细胞之间的信息交流都要通过细胞膜上的受体来实现；②在制备细胞膜的实验中，红细胞一般要先用适量的生理盐水稀释；③用丙酮从鸡的红细胞中提取脂质，在水面铺展成单分子层，面积恰为红细胞表面积的两倍；④中心体是仅由两个相互垂直的中心粒组成的细胞器；⑤生物膜系统是细胞内所有的膜结构的统称，包括叶绿体类囊体薄膜；⑥缺氧状态，叶肉细胞产生的一分子CO₂进入相邻细胞的叶绿体内，穿膜层数是6层；⑦电镜下观察植物叶肉细胞的细胞核，可以看到的主要结构有核膜、核仁和染色体．

我们吃的穿的，哪一样能离开群众的支持？