下句中，只有一处错误，请找出并改正。

I used to is really quiet .

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如图所示大洲，也被称为阿非利加洲．古希腊文“阿非利加”是阳光灼热的意思．据图中提供的信息，图中该大洲与其他大洲的分界线是（　　）

C

My name is Mary. I am an English girl. I'm twelve. My dad and mom are English teachers. I have a brother. His name is Tom and he is thirteen years old. We are in China now. Tom and I are in Beijing No.4 Middle School. Tom is in Class 4, Grade 8 and I am in Class 9, Grade 7.I have a dog. It looks strong(强壮的)．It has a big mouth and two black ears. We have many Chinese friends here. They are kind(和善的).

根据短文内容，判断正误。

已知曲线C: $x^2+\frac{y^2}{b}=1$与抛物线$y^2=4x$的一个交点为M，F为抛物线的焦点，若$\left|MF\right|=4$，则b的值为(    )