A.255m/s;486K;4.56×105paB.250m/s ;480K ;4.56×105paC.300m/s ;450K;4.56×105paD.355m/s;486K;3.56×105pa
A.無(wú)窮大;無(wú)窮大;無(wú)窮大B.無(wú)窮大;無(wú)窮大;有限值C.無(wú)窮大;有限值;無(wú)窮大D.有限值;無(wú)窮大;無(wú)窮大
A.a*2=u1*u2B.a*2=u1-u2C.a*2=u1/u2D.a*2=u1+u2