Điền vào chỗ trống

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Solar energy is a long lasting source  of energy, and it can be used almost anywhere. To generate solar energy, we only need solar cells and the sun ! Solar cells can easily be installed on house (1) ............................ Compared to other (2)............................. sources, they also possess many advantages: wind and water power rely on turbines which (3)........................noisy, expensive and which take up large space. Solar cells are totally silent and (4)............................... As they have no moving parts, they require little maintenance and have a long lifetime.