Question

There are several chemical factories        waste water into the river.
A．pour             B．pouring              C．pours

Answer 1

B

本题的完整句子应为There are several chemical factories that/which are pouring waste water into the river,本题是同时省略主语和谓语，只留下pouring,故选Ｂ，Ｃ为第三人称的单数明显错误，因为前面的主语工厂是复数。