在观察蚯蚓的过程中,要保持蚯蚓身体处于湿润状态,因为蚯蚓呼吸依赖于( )
A:肺
B:体表
C:鳃
A: What can you see? B: I can see two____.A: What colour are they? B: They're____.
如图所示,已知∠B=∠C,AD∥BC,试说明:AD平分∠CAE.
长江发源于____山,流经____、____、____、____(地形区),注入____海,划分长江上中下游的分界城市是____和____,是我国第____长河.长江水能资源丰富,主要集中在____游河段.有____和____之称.