系统性硬化症的病理特点是
A．中、小动静脉血管炎
B．滑膜炎
C．肌炎
D．胶原增殖、纤维化
E．肌腱端炎
参考答案：D
Would it be _____ for you to pick me up at four o'clock and take me to the airport? [ ]
A. free
B. vacant
C. handy
D. convenient
试述哺乳动物骨骼系统有哪些特点？
