KOR ZHI HENG's answer to Hui Ling's Secondary 4 Biology question.

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KOR ZHI HENG
Kor Zhi Heng's answer
63 answers (A Helpful Person)
1st
KOR ZHI HENG
KOR ZHI HENG
6 years ago
air contains 21% Oxygen gas, mind my english in the photo hahaha
Hui Ling
Hui Ling
6 years ago
Thank you very much for your help!!