题如图,在一个玻璃筒两端套上弹性薄膜,竖直浸没在水中,以下说法正确的是( ) (A)两端的薄膜都向内凹. (B)上端的薄膜向外凸,下端的薄膜向内凹. (C)上端的薄膜向内凹,下端的薄膜向外凸.(D)两端的薄膜都向外凸.我们考虑这个问题的时候,如果只分析薄 As shown in the figure, an elastic film is placed on both ends of a glass tube and is immersed vertically in water. The following statement is correct: (A) Both ends of the film are inwardly concave. (B) The upper end of the film is convex outward, the lower end The film is inwardly concave. (C) The upper film is concave inwards, and the lower film is convex outward. (D) The films at both ends are convex outward. When we consider this problem, we only analyze the thin film.