如图，△ABC中，∠ACB＝90°，AC＝3，BC＝4．以A为圆心作圆与BC相切，则该圆的半径为（  ）．

增加：在缺词处加一个漏词符号（^），并在此符号下面写出该加的词。

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。

Dear Editor,

    I'm the only daughter of my parents. So they worried about everything I do. For example, when I ride my bike, my parents won't let me ride by myself. They are afraid of I might fall off my bike and hurt myself. Instead, they are taking great trouble to support a bike, with my mother even carrying a first-aid box. I'm not free to ride and I often say angry, “Why not let me ride alone?” Now, most family have one child. Parents want to do everything for his children. This does no good on them. Too much love from parents may prevent children from become independent. In my opinion, parents should let their children do that they should do alone.

Yours,

Alice

下列关于科举制度的说法中，不正确的是（　　）

已知函数  $f\left(x\right)=x^2+ax,x\in R$．若  $f(x+1)=f(-x)$，求 $a$ 的值；当 $a=2$ 时，求  $g\left(x\right)=xf\left(x\right)$的单调区间．

李明每天上午7：50到校，上午11：30离校；下午2：00到校，下午4：40放学。李明一天在校的时间是____小时____分。