Insects and worms are all invertebrates.昆虫和蠕虫都是无脊椎动物。In the earthworm and many other invertebrates, these excretory structures are called nephridia.在蚯蚓和许多其它无脊椎动物中, 这些排泄结构称为肾管.But regulators with spine are still better th...
The Supreme Court unanimously ruled that racial segregation in schools was unconstitutional.联邦最高法院一致裁定学校实行的种族隔离措施违反宪法。Partitions provided a segregation between the smoking and non-smoking areas of the canteen.隔断把餐厅分成了吸烟区...