语法题：Identify the sentence that is not a run-on,如何做?

英语语法的所谓 run-on 句是两个独立短句之间没有加标点放在同一句子里。比如：Adam is a sweet boy he really loves animals。改正 run-ons 非常简单,在句子里适当的地方加个标点符号即可：Adam is a sweet boy,he really loves animals。