A.There are thirty children in my class.B.There are thirteen children in my class.

【答案】A

【解析】

句意：在我的班级里有30个孩子。A. There are thirty children in my class.在我的班级有30个孩子。B. There are thirteen children in my class.在我的班级里由13个孩子。所以A符合句意，故选A。