什么是run-on sentence

un-on sentence流水句；溶合句；不间断句子；缺乏连接词或标点符号的长句.
两个句子的连接必须用连词或者是分号,用逗号来连接两个句子只能是分句,不是主句.
A run-on sentence is a sentence in which two or more independent clauses (that is, complete sentences) are joined with no punctuation or conjunction.
修改如下：
Obviously, the problem of greenhouse effect is one of the biggest problems that had many big conferences between countries to discussed it today,（这里应该用句号或分号,连接两个完整的句子） （用句号时大写The）the movie is just magnifying the effect of this problem in order to lead the reason of this clime disaster more believable.
Moreover, before the main catastrophe happened in THE DAY AFTER TOMORROW there are many small disasters appeared in the movie, like hail and cyclone which（避免重复可用that） could be seen in the（去掉the,平常生活中in ordinary life） normal life, that（非限定性定语从句用which引导）let the story（缺少谓语动词be或不妨用“makes+形容词”结构更恰当） more closed to people’s experience and give（与前makes并列,用单三形式gives） the audience more soul shock than 2012.
In 2012, the communication between the people is not enough, （逗号可改为冒号：或破折号——表示其后的句子解释说明）the main action in this story is just run--- run on foot, run by car, run by plane and at last run by a huge ship.