【简答题】在生态系统中,各种生物的数量和所占比例是 ( ) 的,生态系统具有( ) ; 生态系统成分越复杂,自动调节能力越强,如森林强于草原、自然生态系统强于人工生态系统。 9.生物圈:地球上所有生物与其环境的总和,范围包括 ( )、( ) ( 距海平面 150米 以内 )和( )( 陆生生物的 “立足点” ) ,约 20 千米厚。( )是 最大 的生态系统。
【单选题】自 20 世纪 50 年代 , 荷兰的兰斯塔德地区经过多次空间规划 , 形成城市在外、郊区在内的空间特征 : 该区中间是一个接近 3 000 平方千米的 “ 绿心 ”—— 乡村地带 ; 四个核心城市和其他城镇呈环状分布在 “ 绿心 ” 的周围 , 城镇之间设置不可侵占的绿地。四个核心城市各具特殊职能 , 各城市分工明确 , 通过快速交通系统连接成具有国际竞争力的城市群。近 20 年来 , 该地区城...
【单选题】Transplant surgeons work miracles. They take organs from one body and integrate them into another, granting the lucky recipient a longer, better life. Sadly, every year thousands of other people are l...
A.
they are unlucky patients
B.
organ transplantation is unreliable
C.
there are not enough proper organs for transplantation
D.
few people are willing to donate their organs after death
【单选题】Who benefited the least from fridges according to the author?
【简答题】Who benefited the least from fridges according to the author?
【单选题】Students are offered with opportunities to integrate what they learned from the text into their existing knowledge and communicate with others using the information in the listening text. This descrip...