That day I saw some parents__at the back of the classroom,__to the teacher carefully.

问题描述:

That day I saw some parents__at the back of the classroom,__to the teacher carefully.
A sitting,listened B sat,listend C sitting,listening D sat,listening选什么?

C
前面是与see搭配的结构“see sb doing sth”,意为“看见某人在做某事”;
后面是现在分词表示伴随的动作,我们把这种结构叫 伴随壮语.
句意:那天,我看见一些父母正坐在教室的后面,认真的听老师说话.