判断题：根瘤菌具有固氮作用。（  ）

有一位科学家分离到一种动物细胞的细胞膜，他将膜放在特制的仪器中，分隔两边装蒸馏水的槽。当他将稀释的乙酸放入一侧时，发现另一侧槽中的pH没有变化。于是他将动物细胞匀浆磨碎，过滤出细胞器和膜的碎片，然后再将滤液加到加过乙酸的一侧，这时发现另外一侧的pH下降了。造成这种变化的最合理的解释是(　　)

南亚产生旱涝灾害的主要原因是（    ）

阅读理解

    Look, there are some special days in April. April Fool's Day is on April 1^st. Children will have fun on that day. Easter is also in April. There will be an Easter party. Children will play many games. They will roll (滚动)Easter eggs and meet the Easter Bunny. What a happy party! When is the sports meet? It's on 21^st . That will be fun too. Everyone loves April.