_________ quite well in the important exam, he came back home, _________ and smiling.
A:Having done; relaxed
B:Having done; relaxing
C:Having been done; relaxing
D:Done; relaxed
如图是探究影响酵母菌种群数量变化因素时获得的实验结果.有关分析不正确的是( )
下列说法正确的是( )
生态系统一般都包括( )