____A. Happy birthday!
____B. How old are you?
____C. How many plates?
____D. Here you are.
____E. Show me nine.
按学习行为的复杂程度由低到高排列,正确的是( )
如图为我国部分经济作物主要分布区示意图,图中①、②表示的经济作物分别是( )