如图，在梯形ABCD中，AB∥DC，AD=DC=CB，若∠ABD＝25°，则∠BAD的大小是 (       )  

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In our city, there is a big zoo. There are a lot of different animals in it. There are some scary(吓人的) tigers and lions. They like eating meat and they eat much meat every day.
There are also two big elephants and a baby(幼崽) one. Children like to ride one of them. The elephants are very kind and friendly. They eat much grass and bananas.
In the zoo, we can see different kinds of bears(熊): brown bears, black bears and white bears. They are all shy and clumsy(笨拙的). They stand on their back legs and lift their front legs to ask for food They like cakes very much.
Do you like pandas? There's only one in the zoo. Her name is Lingling. She is very cute. She likes eating bamboos a lot. She is kind of shy, She's very interesting and lovely.

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某滑轮组改进后提高了机械效率，用这个滑轮组把同一个物体匀速提高到同样的高度，改进后与改进前相比（　　）