By the time she got outside, the bus _____. [ ]
A. went
B. gone
C. has gone
D. had gone
答案:D
在热带雨林生态系统中,下列说法不正确的是()
A.动植物种类繁多,群落结构复杂,自我调节能力强
B.高温多雨,分解者活动旺盛
C.恢复力稳定性比草原生态系统强
D.当其遭受持续干旱气候时,往往扩展根系分布空间,以获得足够水分,这属于生态系统的抵抗力稳定性