Chọn hệ số thích hợp (giải thích ) a) NxOy + Cu ----- CuO + N2 b) FexOy + H2 ------- Fe + H2O c) CxHyOz + O2 ------- Co2 + H2O

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I think you should buy _____  pack of mineral water instead. And you can also buy _____  snacks such as potato crisps, 3 kilos of mandarins, 2 kilos of apples, 3 bunches of bananas, ______  cookies and soft candies.

Choose the best answer.

We should decorate our living room with _____ orange banner. We also need ________  ribbons, balloons, party hats and costume.

Choose the best answer.

I think that ______ cauliflower is not enough for 3 people. Let’s buy one more.