恶性骨肿瘤的临床特点有
A．生长迅速
B．无症状或有轻微症状
C．X线示边缘清晰，无骨膜反应
D．骨质破坏
E．可经淋巴转移
参考答案：A,D,E
Air is to human _____ water is to fish. [ ]
A. that
B. what
C. which
D. where
系统采用跳频时的C/I门限值为（）
A.9dB
B.12dB
C.-9dB
D.3dB
