题目

生态系统中能量，能量沿食物链各个环节传递时，其特点是（   ） A．单向传递，逐级不变                                 B．单向传递，逐级递减 C．循环流动，逐级增加                                 D．循环流动，逐级递减 答案：B–Well, Randy is not quite ready to make a decision. --So, ___, we have to wait, right?A．on the other handB．in other wordsC．for example D．in some ways