Since then, she has managed to get only one or two home-based accounting projects, which paid about $90 each.

Over the years, Miss Sia lost touch with her friends and former schoolmates. She cannot remember the last time she went out with friends without Jin Zhu.

Miss Sia, who has never had a boyfriend, said: 'Even back in school, I found that circumstances forced me to grow up much faster than my peers.

'My friends could not understand why I couldn't leave the caregiving to my mother, or to a maid, or relative.'

Miss Sia is meticulous in caring for her sister. She does not allow her to eat certain food such as chocolates, crackers and fast food.

She cooks food with little oil and makes sure they have been properly chopped so the girl can chew easily.

Miss Sia said: 'Jin Zhu's immunity is low, so when she falls sick, she takes longer than normal people to get well.'

Last August, the girl got a cough which lasted 10months. She was warded for eight days at KKH, where a tube was inserted into her lungs to remove phlegm.

That was why Miss Sia did not allow her to go to school since June this year, because she did not want her to fall sick during the PSLE.

A classmate handed her relevant notes and revision papers, and Miss Sia then helped Jin Zhu to study at home.

Her efforts paid off when Jin Zhu scored an aggregate of 220 for the PSLE, and made it to the express stream of Greenridge Secondary School.

Worsening health

But the girl's health is slowly taking a turn for the worse.

Weighing a mere 17kg now, Jin Zhu is due for surgery next month to insert metal rods into her back, as doctors said her spine could possibly collapse onto her lungs, making breathing difficult.

The surgery is expected to cost about $22,000, with the bulk being paid by a relative's Medisave.

Miss Sia said: 'Doctors have said that Jin Zhu may live to 30 or 40 years old if we take good care and don't let her fall sick.

'What we fear is that her body may deteriorate to the point where she has trouble breathing on her own.

'We don't know when that day will come, hopefully never. I want her to study well, so she can become a useful person.'

When The New Paper visited the family last week, Jin Zhu appeared cheerful, shouting 'hello' and waving at us from her bed in the living room.

The girl confidently showed us how she could correctly answer questions in an English paper for Secondary 4 students.

When we congratulated her for doing well in the PSLE, she smiled and said: 'I did okay only. My sister helped me.'

Miss Sia does not feel her efforts are a 'sacrifice'.

'I'm glad my mother no longer feels guilty and depressed over Jin Zhu's ailment. I'm glad Jin Zhu is now a cheerful and confident girl who is not afraid of strangers,' she said.

'I don't feel I've lost anything in caring for my sister.'

This article was first published in The New Paper on Decemember 15, 2008.