All attention on the beautiful girl, the boy didn’t notice the teacher enter the classroom.
A. focusing
B. focused
C. to focus
D. was focused
网友回答
A. focusing
(答案→)B. focused
C. to focus
D. was focused
解析：考查独立主格结构：句意：所有的注意力都集中在漂亮的女孩身上，男孩没注意到老师进入教室。逗号后面是个简单句，因为没有连词，所以前面不是句子，而是独立主格结构做状语，all attention和focus是被动关系，用过去分词，选B。