城市生态系统是以________为主体,与__________、_________相互作用的统一体,是一个复杂的______生态系统。
人 自然环境 社会环境 人工
I hear you’ve got a pen pal. Could you tell me ___________? [ ]
A. where does she come from
B. where will she work
C. what her name is
D. How did you know each other
增值税征税范围中的无形资产包括()。
A.机器设备
B.专利技术
C.非专利技术
D.著作权