生态系统越复杂，生物之间的流动和循环越随意，所以抗外界干扰的能力越弱。
参考答案：错
My shoes ____________ under the bed just now. But they ____________ there now.[ ]
A. are, weren't
B. were, weren't
C. were, aren't
臧克家的诗歌《老马》在艺术上用了（）手法。
A.对比
B.类比
C.象征
D.联想
