问题补充:
The children were playing games on the playground, school uniforms.
A. all of them wore
B. all wearing
C. all of whom wearing
D. all were wearing
答案:
A. all of them wore
(答案→)B. all wearing
C. all of whom wearing
D. all were wearing
解析:句子中没有连词,所以排除A,D;而C选项不是完整的定语从句,所以选B,用动词的ing形式。