下列物质中,能用作氮肥的是
A.K2SO4
B.CO(NH2)2
C.K2CO3
D.Ca(H2PO4)2
B
题目分析:CO(NH2)2含有植物需要的营养元素N,属于氮肥。应选B项。
They know a lot about animals, but they want to know _________ about them.[ ]
A. many
B. much
C. more
D. some
计算:(﹣12)﹣5+(﹣14)﹣(﹣39).