YUNNAN, June 7 (Xinhua) -- As the students stepped cautiously into the teaching building on Thursday morning for their college entrance exam, Li Xiaofeng, a 35-year-old female teacher in quake-hit Ning'er County in southwest China's Yunnan Province, uttered a loud sigh of relief.

"Some of my students are from very poor families, and they were really worried they wouldn't be able to take the exam," said Li, standing outside Pu'er Middle School, the only college entrance exam venue in Ning'er County.

On Sunday a powerful earthquake, the most serious in Yunnan since 2001, ripped through the region, destroying houses and leaving 186,000 homeless. Three people died in the quake and nearly 300 were injured.

"But the quake hasn't stopped them taking the exam, their dreams of a college education are still intact," said Li.

Almost 700 teenagers from Ning'er county started their all-important national college entrance exam just like teenagers in other parts of the Chinese mainland -- the only difference was the 80 tents lined up beside their exam building. With the region registering 1,422 aftershocks since Sunday, the tents are backup exam venues.

Cracks are clearly visible on the external walls of the teaching building.

County education bureau chief Xu Huaming said: "The buildings are solid so we consider the classrooms safe to use. Aftershocks have been below five on the Richter scale and are petering out, but we still have to ensure 100 percent safety for our students."

He said that, in case of an aftershock, students can continue the exam in the tents.

Exam proctors this year have learned new measures to handle emergencies, including first-aid and evacuation procedures.

Li has been living with her 200 students in tents for the past four days, with four to five students in each tent.

Each tent has two windows and a door but ventilation is not great, said Li.

Inside the tent, wooden boards are propped up on bricks to make beds, with neatly folded quilts on top. Some of the girls have picked white gardenias and put them in a bottle, adding a fragrant scent.

Teachers helped put up the tents on Sunday night during a downfall, recalled Li.

"When rain seeped into the tents on Wednesday afternoon, the teachers dug a channel to divert the water," said Li.

"What I worry about most is my students' getting a good night's sleep, and also the mosquitoes," said Li. "I tell my students that they can succeed in the exam if they eat well and sleep properly. All the teachers are doing their best to ease conditions for them."

With dark rings under her eyes, Li watched her students file out of the classroom at 11:30 a.m. after finishing their Chinese language test.

Some of the students told Li Xiaofeng that the essay topic for this year was "Gratitude".

"I hope you thought of something to write about," said Li, with a grin.