有关长江的叙述，不正确的是（　　）

请给我一个汉堡包。

    Scientists say life will be very different in 2050.

    First，there will be no TV channels（频道）in 2050.People will choose a program from a computer and watch it on TV.In 2050，we will get information from the computers only.

    Second，water will be a big problem in 2050.In many places，people won't have water to drink.

    Third，cars will use new and clean fuels and they will go very fast.There will be a computer in every car.And the computers will control the cars and there won't be any accidents（事故）.

如图，如果从半径为9cm的圆形纸片剪去$\frac{1}{3}$圆周的一个扇形，将留下的扇形围成一个圆锥（接缝处不重叠），那么这个圆锥的高为   (      )