[问答题]
1.Draw and label a trophic py 3 gp)p vy(r+3nz 4hh;fdlu.ky* 6ssgnd:x2gsy(9rw l zjxh4,ramid of energy showing four levels.
2.Explain how the presence of a food web in an ecosystem makes it more stable than the presence of a single food chain.
3.The production and transfer efficiency of energy varies between ecosystems.
Describe how energy flows in and out of terrestrial ecosystems.
