单项选择题
A.dead leaves and tree debris make the same sound B.trees that are dying usually give out a soft moan C.organic debris echoes the sounds in a rain forest D.the sound of a forest signifies its health condition
A.They suffer great losses in stocks, property and other assets. B.They find the self-correcting mechanisms dysfunctioning. C.They are afraid the normal social order will be paralyzed. D.They don’t know what is going to happen in the future.