Showing ______ to a current or former teacher is a fair reward and an act of gratitude that will

also make you feel better.  [ ]

A. appreciation        

B. enjoyment      

C. delight        

D. pleasure

不适于水田施用的氮肥是（）。

A.氯化铵

B.硝酸铵

C.硫酸铵

D.碳酸氢铵