一个不透明的袋子中有3个分别标有数字3，1，﹣2的球，这些球除所标的数字不同外其它都相同．若从袋子中随机摸出两个球，则这两个球上的两个数字之和为负数的概率是____ 

假定英语课课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。每处错误仅涉及一个单词的增加、删除或修改。

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8处，多者（从第9处起）不计分。

    Now bike-sharing is becoming increasing popular. It is green means of transportation and provides a user-friendly experience. Besides, problems also arise. The bicycles are left almost in everywhere on the street. Also, many people ride the bicycles on the driveway, cause many traffic accidents. My suggestions on how to improve the situation were as follows.

    First of all, the city government should design certain areas for parking the bicycle. In this way, fewer people will leave the bicycles like they please. Secondly, more roads for bicycles needs to be built to make sure that cyclists aren't caught in a traffic jam.

    I hope this bike-sharing project will help build better traffic or improve the air quality.