氧气维持这我们的生命，在我们人体的各部分结构中，O₂浓度从小到大的顺序是（　　）

①肺泡          ②静脉血          ③动脉血            ④组织细胞．

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。

    An opening week held in our school last week so that we could show a great achievements we made in art education.

    The art works exhibition went on from Monday to Friday, exhibit the excellent art works, such as paper cuts, paintings and flower arrangements. Both of the art works were created by the students of our school. That attracted the public most was the singing and dancing performances in Friday afternoon. All these activities draw the close attention of the public and parents as well, receiving high praises from the public.

    Through these activity, the public has a better understanding of our school. As a result of ,we all think that the opening week was of great successful.

萤火虫吃蜗牛时，先把蜗牛分割成一块一块，再咀嚼品味。

如图，长方体ABCD-A₁B₁C₁D₁中，AB=16，BC=10，AA₁=8，点E、F分别在A₁B_1、C₁D_1上，A1E=D_1F=4，过点E,F的平面$\alpha$与此长方体的面相交，交线围成一个正方形。