天然森林很少发生松毛虫害，近几年来，某人工马尾松林常发生严重松毛虫害，其主要原因是

在给定椭圆中，过焦点且垂直于长轴的弦长为$\sqrt{2}$，焦点到相应准线的距离为1，则该椭圆的离心率为（  ）

将下列句子填入语段的划线处，顺序最恰当的一项是（    ）
但是，没有人会喜欢只有灰色的世界。                      多彩保证了活力，而灰色提升着品位。这也就是和谐。
①这世界充满生命活力，姹紫嫣红，千姿百态，万类霜天竞自由。    ②灰色也只有在和其他色彩搭配时，才能显示它的普适性，显示它的高贵和纯粹。      ③也正因为有了思想的高贵、纯粹，纷繁的世界才不至于俗不可耐。   ④正因为有了生活的五彩缤纷，理论的灰色才不显得死寂     ⑤因此，灰色又必须链接多彩的世界。

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。

    Yesterday morning, I heard a piece of news which my friend Li Lei was admitted to the hospital because of the car accident. The day before yesterday, Li Lei is going to a bookstore to buy a book. He was very carefully when he got to the crossroads. He crossed the street when the traffic light turned to green. However, if he just went to the middle of the street, a car suddenly appeared at his right-hand side and came directly towards him. The driver drove fast and it was too late to avoiding it. Li Lei was knocked by the car. She was carried to the hospital immediately and had a surgery. Last night, I visited him. He looked pale unless he was out of danger.