【简答题】We need to rethink the way we consume energy. Take, for ________, our approach to transport.
【单选题】We are all aware _________ the many threats _________ the environment and we need to take action to pr us from the bad consequences.
【单选题】We need not these flowers anymore, please ________. [ ]
【简答题】空气的击穿场强为3×103KV/m。当一个平行板电容器两极板间是空气而电势差为50KV时,每平方米面积的电容最大是多少? 而 。