[填空题]
An ocean fishing boatcccmq +fo q0i( i8c6t4l1y2mw i(e+ofsf 2vb1 hs drifting just above a school of tuna on a foggy day. Without warning, an engine backfire occurs on another boat 1.0 h2+ fes(b 1fvokm away (Fig. 12–33). How much time elapses before the backfire is heard (a) by the fish, s (b) by the fishermen? s