平行四边形的面积是（   ）

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。

    Ten years ago, I was lucky enough to have an opportunity to study in England as a international student. I went to one of the most famous school there. On the first day, I was such nervous that I felt my heart beaten wildly. I was afraid to express to myself, because I have never communicated with strangers in English before. Therefore, my teacher said I had to introduce me in front of the class. As soon as the first word flew out my mouth, I felt relaxing immediately. I was happy I finally made it. It's a special day, which I will never forget.

下列命题中：①有理数是有限小数；②有限小数是有理数；③无理数都是无限小数；④无限小数都是无理数。正确的是         （       ）