[Photo/Guangzhou Daily]

They are not performers, but senior high school students preparing for gaokao, or National College Entrance Exam.

This photo, published on Sina micro blog on Tuesday, was widely distributed and attracted many comments. They are students from Dongguan No 5 High School.

"This photo was taken in hot weather and under pressure of exams," said the micro blogger who published it.

The schoolmaster, Ye Zhaolun, expressed mixed opinions about it. "The hardworking spirit is worth encouraging. But the photo may evoke misunderstanding and stir controversy and thus distract students' attention," Ye wrote on his micro blog.

"It's becoming more common to install air-conditioners in classrooms. But currently finance does not allow it," he said.

Internet users expressed their own opinions:

"Their hardworking spirit is worth learning," wrote micro blogger Shuangweiweijuan.

"Schools should try to take cool measures for students. Studying half-naked is not tidy or clean, and students may also catch a cold," wrote Guyunshujuan.