A.1.5tmax B.1.5min C.1.5tmax-1 D.1.5max+13-17
A.分別取1.0、1.22 B.分別取1.22、1.0 C.均取1.0 D.均取1.22
A.βf=1.0 B.βf=1.1 C.βf=1.22 D.1<βf<1.22