[填空题]
If the velocity of blood flow in the aorta is normally alrca/+xe2c y tt)ra3- bout 0.32 m/s what beat351)*g .u hvavpgu;r, iqjt fw frequency *jav)1q.hw3g uf; pt5rv,igu would you expect if 5.50-MHz ultrasound waves were directed along the flow and reflected from the red blood cells? Assume that the waves travel with a speed of $1.54 \times10^{3 }$ m/s $ \times10^{3 }$Hz
