读“我国东南沿海某区域附近地区地形图和河流剖面示意图”,回答下列各题

米酒是一个传统的小吃，制作米酒是，在米饭里要渗入一些酒曲，其原因是（ ）

如图所示，闭合开关，两灯都不亮．为检查故障，某同学先用电压表与灯L₁并联，观察到电压表无示数，再将电压表与灯L₂并联，观察到电压表有示数，那么电路中出现的故障是（ ）

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：在错的词下面画一横线，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 Mike,

    How happy we are to know you're going to participate in our Chinese Idiom Contest. Here are what you are supposed to know about.

    The contest will be hold in the school library at 8:00 a.m in July 15, 2018. Characters wrong used should be recognized in some Chinese idioms. Besides, you are required say out the idioms by guess gestures of your partner. Hopefully, why I have to remind you of is that you'd better to get one story idiom prepared in case you are probably invited to tell one. By the way, all our Chinese teachers will be invited as judge.

    Expect your excellence performance in the approaching contest.

    Best wishes!

Yours,

Li Hua

设f（x）是定义在R上且周期为2的函数，在区间﹣1，1上，f（x）=$\left\{\begin{array}{c}ax+1,-1\le x<0\\ \frac{bx+2}{x+1},0\le x\le 1\end{array}\right.$其中a，b∈R．若$f\left(\frac{1}{2}\right)$=$f\left(\frac{3}{2}\right)$，则a+3b的值为____