单项选择题
A.T1越短信号越强;T2越短信号越强B.T1越长信号越强;T2越长信号越强C.T1越短信号越强;T2越短信号越弱D.T1越长信号越弱;T2越长信号越弱E.T1越短信号越弱;T2越短信号越弱
A.形状B.重量C.体积D.频率E.密度
A.0.5B.0.75C.1.25D.1.5E.1.75