环境作为环境保护的对象，其主体是( )。
A．人类B．自然环境C．社会环境D．政策环境
参考答案：A
Last week, Susan and David, ________our university's student association, met the Chinese guests
at the New York airport. [ ]
A. to represent
B. representing
C. represented
D. having represented
试述TIA的治疗。
