Here are some facts about homes in the United States and the people who live in them. In the early 1990s, about 50% of the Americans own their homes and the rest rent(租) their homes. The rented homes are usually apartments(公寓).
   74% of the people in the US make their homes in or around cities. 26% live in the country. Dogs live in about 40% of all homes in the US. About half that number have cats.
   Families in the US are becoming smaller. On the average（平均）,2.64 people lived in a home in the early 1990s. In 1960, the average was 3.5.
   Half of the teenagers in the US have their own bedrooms.
   An American moves, on the average，twelve times in his or her life. In Japan, a person moves about five times, and in England a person moves eight times.

根据密度公式$\rho$＝$\frac{m}{V}$，对于相同的物质，下面说法正确的是（   ）

读一读，描一描。

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