2Cu + O2--to>2CuO4K + O2--to>2K2OC + O2--to>CO24P + 5O2 --to>2P2O5
2Cu + O2 → 2CuO
4K + O2 → 2K2O
2C + O2 → 2CO
4P + 5O2 → 2P2O5
Choose the best answer.
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Please turn off ___ lights when you leave ___ room.
I like _____ colorful costumes of ____ ethnic minority people in Vietnam.