I often go to school .A. by bus B. by buses C. by a bus

问题补充：

I often go to school .

A. by bus B. by buses C. by a bus

答案：

解析：本句的意思是“我经常乘公共汽车去上学。”在英语中表示“乘某种交通工具”可以用“by+交通工具”，中间不能用冠词，名词也必须用单数。所以本题选A。