— Who are they? — .
A:They were my parents.
B:They are my parents.
C:It's my parents.
若且,则的最小值是:( )
近几年来,反常天气出现在世界各地,显示出全球气候变暖的趋势,其主要原因与碳循环不平衡有关,如图是生态系统中碳循环模式图,其中A、B、C、D表示生态系统的某种成分;①②③④⑤表示某些生理过程.请据图回答:
Class is over. The students stop and start .