BEIJING, June 7 (Xinhua) -- She was not going to a grand party or office meeting, but 25-year-old Lin Xiao had checked her dressing once and again before leaving home Thursday morning.

No tank top, no cartoon or English printed T-shirt, and no clattering high-heeled shoes. Only after making sure that she had nothing of the taboos on her did Lin go out, with a sigh and a smile.

The no-nos Lin had to observe were just a small part of an omnifarious checking list for tens of thousands of invigilators for China's national college entrance examination that began on Thursday.

The annual matriculation examination, called "gaokao" in Chinese, is regarded as an event when millions of youngsters would seek a chance for change of life in this fiercely competitive society.

More than 9.5 million candidates would compete in the world's largest examination this year, but only 5.67 million would be able to enter college, according to the Ministry of Education.

Lin, an invigilator at the Beijing No.101 Middle School, received the "taboo list" from exam organizers two days ago, which asked them to be cautious with their dressing so as not to distract the attention of the candidates.

All the exam venues in Beijing had similar lists for invigilators , ranging from "no perfume" to "no cough".

Lin, who had the same examination eight years ago, said today's gingerliness was somewhat overdoing.

"Why are we so nervous about the exam and these teenagers? I don't understand," said Lin, in a white shirt.

"Are today's children so fragile that even a cough from us will distract them from their test papers?" Lin complained, saying that when she took the exam, the atmosphere was not so tense like today.

"I think excessive care will only make the children more nervous," said Lin.

In Beijing, traffic was filtered on Thursday to ensure students could arrive at venues on time.

Their anxious parents waited nervously outside the exam venues in temperatures above 35 degrees Celsius.

The Chinese capital is not alone. Many other cities have similar or more strict regulations to ensure a "quiet and relaxed environment" for candidates.

In Huangshan City, east China's Anhui Province, a flight was required to change route on Thursday afternoon, as parents worried the noise could affect their children's listening comprehension in the English test.

More than 600 police motors were mobilized in Chengdu, capital of southwest Sichuan Province, to help provide transport service to candidates.

Some nervous parents in Shanghai searched before the exam for a prescription stimulant to give their children. They hoped the drug, Ritalin, could help their children concentrate on the test papers and boost their performance.

"All other things must give way to the exam, the pitiful children are undertaking unbearable care," said Lin Xiao.

This year marks the 30th anniversary of the restoration of the national college entrance examination. Chinese universities stopped enrolling students from 1966 to 1976, due to the political turmoil of the Cultural Revolution.

Over the past three decades, almost 60 million Chinese have taken part in "gaokao", with 10 million enrolled at universities.