A:化肥
B:氧气
C:光能
D:二氧化碳
凸透镜对光有 ____作用(选填“会聚”或“发散”).凸透镜的焦点为F,当蜡烛如图所示放置时,在透镜另一侧可成一个 ____、放大的实像(选填“倒立”或“正立”)
我国各民族中,人口最多的是( )
As we grow up, it always _______ that after we give something up, we gain something new in its place. ( )
有关洋流对地理环境影响的叙述,正确的是( )