LEAVING Shanghai to live in Hong Kong, adapting to the unfamiliar living environment here, smashing the language barrier, catching up with the English-based education - all of these obstacles could not stop Queen Elizabeth School student Cheung Oi-mui from scoring nine As in the HKCEE. The 18-year-old Economics student first set foot on the territory when she was nine, leaving all her friends and relatives behind. ''But I managed to get through this dramatic change real fast mainly because my primary friends were very nice and accepting. Before long I could speak fluent Cantonese,'' Oi-mui said. Oi-mui, who scored A(1)s in Chinese Language, Geography, Economics, Biology, Chemistry, and Physics, and A(2)s in English Language, Mathematics and Additional Mathematics, did not dare dream she would get such good results. ''I did not start preparing for the exam until January. But once I got through the mock exam in March, the momentum was gone. Luckily, I managed to pick up the incentive again later on when I realised how much I had fallen behind my classmates.'' The Cheung family owns a fast-food restaurant, thus supporting Oi-mui and her Form Three sister. Oi-mui attributed her success to the encouraging study atmosphere in school, with teachers willing to sacrifice after-school hours to do extra tutoring. ''I was so impressed by the teachers who sometimes cancelled their dates and dinners to teach us after school.'' But Oi-mui put in much effort, too: she studied so intensely she did not leave her room for days. ''During the Chinese New Year holiday, I locked myself in my room for the whole period and did nothing but study. Sometimes my mum worried about me for such harsh studying but I comforted her that I was doing all right.'' After all that mental effort, Oi-mui would play squash and volleyball, her two favourite sports. Asked about her plan for the future, she said: ''I think I will study business administration in Hong Kong and see if I want to go on studying or start going right to work after university education. But I still have to wait and see where my interest will go at that time.'' Meanwhile, another Queen Elizabeth student, 17-year-old Si Mei-mei, scored eight As: A(1)s in Chinese and English, Biology, Chemistry and Physics and A(2)s in Mathematics, Additional Mathematics and Computer Studies. Mei-mei, who has been playing the piano for eight years, believes her piano lessons have helped her to build up a patient personality. She plans to study engineering in the United States, but says she will definitely return to Hong Kong after 1997.