题目

“Here, waiter! Look at your soup. What’s this? Is it vegetable soup? No. It’s fly(苍蝇) soup! Look at the bluebottle! Terrible! Pour it onto the face of the cook. Who wants such a wonderful soup?” shouted a middle-aged lady. In less than a second, the customers gathered around her table. A young waiter was already holding the soup plate, searching for the fly with a spoon. The lady was angry. The manager came out to see what the trouble was. “Bring her another bowl of soup” was his order. The lady wanted to show the fly to the manager. As she reached for the spoon, she pointed at9．尿素[化学式[CO（NH2）2]等植物营养物质过多进入水体会恶化水质，导致“水华”现象．尿素属于（　　）A．混合物B．氧化物C．氮肥D．复合肥