Phép cân bằng phương trình hóa học nào dưới đây là sai. A.2K+O2--->K2O. B.Na2CO3+2HCl--->2NaCl+CO2+H2O. C.2C+Fe3O4--->3Fe+3CO2. D.Fe2O3+3H2--->2Fe+3H2O.

Choose the best answer.

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.