语法上，这三句改一下：
1。In historical context of the phrase comes from the old railroad and gold rush days of California, where many Chinese。。。。。。
2。There are many things went wrong in that unfortunate night of Nov 20, 2014.
3. Apparently those rookies did not receive adequate training before they were assigned to such task
内容上，不好多动。但这两句：
“while inside a pitch dark stairwell Liang’s gun accidentally discharged.”I would say, "discharged arguably by accident"
Such highly prejudicial and inflammatory argument should not even be allowed in any case. （指控太强了。）
总的感觉，文章应该围绕两个方面 1。如你文中所言，把责任转到楼道黑上。至于这样推卸责任是否合理，另说阿。2。应该多给出华人受到的不公正待遇的事例。这个，论述得比较弱。
