某学生量取液体，仰视读数为30mL，将液体倒出一部分后，俯视读数为20mL，则该同学实际倒出的液体体积为（  ）

读下图判定（    ）

北宋的建立者是（  ）

增加：在缺词处加一个漏词符号（∧），并在此符号下面写出改加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横钱，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。

    Li Hui, my friend in high school,has dreamed becoming a cartoon artist since she was young. To her disappointed,her parents don't agree with her decision at first Therefore,Li Hui would not change her mind.She worked hardly to perfect her skills.Just before he finished high school,the chance came:the famous art school was holding a cartoon drawing competition The first three winners would be given a scholarship to study drawing there. Li Hui told herself not to missing the chance.She readily entered the competition and came second. She is now a student in that school and I feel certain what her dream would come true.

一个直角三角形的三条边长分别是3分米、4分米和5分米，这个三角形的面积是____平方分米