OG207答案是否有run-on错误？

207. In the textbook publishing business, the second quarter is historically weak, because revenues are low and marketing expenses are high as companies prepare for the coming school year.

(A)           low and marketing expenses are high as companies prepare

(B)           low and their marketing expenses are high as they prepare

(C)           low with higher marketing expenses in preparation

(D)           low, while marketing expenses are higher to prepare

(E)           low, while their marketing expenses are higher in preparation

key is A.但是 revenues are low and marketing expenses are high 这个句子中的and前没有加逗号，不是犯了run-on的的错误么？

up! anyone please respond.

有这种说法吗?

请注意run-on错误的定义:

A RUN-ON SENTENCE (sometimes called a "fused sentence") has at least two parts, either one of which can stand by itself (in other words, two independent clauses), but the two parts have been smooshed together instead of being properly connected.

这题里面的and连接的是原因从句, 即dependent clauses, 根本不在run-on的定义范围里面, 也就不可能是run-on错误.

不同意罗德版主的解释，and这里不是连接原因从句，只是because原因从句中的两个并列分句，后半分句可以理解为省略because。

In the textbook publishing business, the second quarter is historically weak, because revenues are low and （because）marketing expenses are high as companies prepare for the coming school year.

这里假如加上逗号的话，会出现and不知与主句还是because从句并列的岐义，但是可以补全省略成分，再加上逗号。

In the textbook publishing business, the second quarter is historically weak, because revenues are low ，and because marketing expenses are high as companies prepare for the coming school year.

不知大家是否能理解我的看法。

In the textbook publishing business, the second quarter is historically weak, because revenues are low ，and because marketing expenses are high as companies prepare for the coming school year.

其实这样写感觉也挺怪的。

感觉OG写的清楚：A对比了low和high

because revenues are low and marketing expenses are high as companies prepare for the coming school year.

我记得两个完整句子用and连接，and前面是要加逗号的啊，怎么这里没有呢？

这样不算错吗？这个规则应该怎么应用呢？

两个独立的句子不一定要用逗号分开，比如两个简单句子可以用and等连接词连接，and前的逗号可有可无。

Rule 12. Using a comma is optional to separate two sentences joined by a coordinating conjunction—and, or, but, for, nor.
Example：

I have painted the entire house, but he is still working on sanding the doors. OR
I have painted the entire house but he is still working on sanding the doors.

本题中and连接的是两个并列的原因状语从句，如果用逗号分开，反而会出现最后一个句子和前面的两个句子中哪一个并列的歧义。而且两个原因状语从句意思形成对比，关系密切，还是不分开的好。