At the 1924 Olympic Games in Paris，the sport of canoe (划船) racing 61.________(add) to the list of international competition. As the time for the Olympics neared，it became clear that Bill'
Have you ever run into a careless cell phone user on the street? Perhaps they were busy talking, texting or checking updates on WeChat without looking at what was going on around them. As the
） m/s或20（n+
） m/s(n=0,1,2,3，…)
)λ
)λ/t=
m/s=20(n+
) m/s.
)λ,因此波速的可能值满足：
)λ/t=(n+
)×4/0.2 m/s=20(n+
) m/s