1. The cloud formation covered the sun.
    云层遮住了太阳。

2. Or protect them from sharks by surrounding them in defensive formation.
    或在人们周围列队保护，使他们免遭鲨鱼伤害。

3. His studies with rats have demonstrated two primary effects of activity: vigorous physical exercise provides the brain with more fuel, and skill-based exercise increases the formation of connections in the brain, which, according to the proposals of
    他对老鼠的研究已经表明运动具有两大功效：强力体育运动给大脑提供更多的燃料，而技巧性的运动则增强大脑神经的联结。依照某些科学家的见解，这种联结能使大脑更好地处理信息。