---Bob, have you packed yet? --Yes, Mum. ---Look over and _______ that you have taken everything you need. A. look for B. make sure C. find out D. work out 答案:B图为某一生态系统的能量金字塔,其中Ⅰ、Ⅱ、Ⅲ、Ⅳ分别代表不同的营养级,E1、E2代表能量的形式。下列叙述正确的是 A.Ⅰ是初级消费者 B.Ⅳ为分解者 C.E1为太阳能,E2为热能 D.能量可在食物链中循环利用