Waste paper shouldn’t everywhere. It’s our duty to keep our classroom clean. A. be thrown

问题补充：

Waste paper shouldn’t everywhere. It’s our duty to keep our classroom clean.

A. be thrown B. throw C. is thrown

答案：

解析： 本题的含义是不应该到此乱扔废纸，should为情态动词后加动词原形，本题前半句表示被动的意思，结构为be+过去分词，故本题选A。