读岛屿的经纬网和等高线地形图，回答问题。

短文改错。文中共有10处语言错误，每句中最多有两处。每处错误涉及一个单词的增加、删除或修改。

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：在错的词下面画一横线，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 Xiaohua,

    It is four days since mother recieves the operation. She is feeling much more better. The doctors told me the operation was successful, but because her old age she had to stay in hospital for other two weeks. The doctors also say it was quite necessary for him to do so. We expect to get a full report in two and three days. Please tell the good news to the rest of the family as soon as possible. You need't come here. I'm able to look at mother by myself. You can send some flower to her. She will feel very happily.

Yours,

Xiaohua

我国北宋至和元年(公元1054年)3月的某个清晨，在东方“天关”附近(金牛座的位置)突然出现了一颗“客星”，其“昼见如太白，芒角四出，色赤白”，司天监(当时的国家天文台)对这颗“天关客星”用肉眼连续观察了两年之久，直到看不见为止。19世纪，人们用望远镜发现在这个方向一有一个“蟹状星云”。20世纪初发现这团星云在膨胀，由膨胀速度率推算，公元1054年刚好是膨胀开始的时刻。阅读上述文字，你认为下述猜想不正确的是(    )  

—To keep the students safe on their way to school, we have taken more action.

— That sounds great. We should do what we can __________ the school bus accident.

下列有关染色体，DNA，基因、性状的叙述中哪一种错误（   　）