题目

In class, students are sharing their dream jobs.Jacob: I'd like to be a mountain-climbing guide for several reasons. Number One, mountain climbing is very exciting. Mountain-climbing guides get to climb tall, dangerous mountains, right? Number Two, I enjoy working outdoors and helping others. Number Three, mountain-climbing guides travel widely and meet many fun people.Fred: My choice is to be a vet（兽医）. Why? I like animals. Animals bring a lot of joy to our lives, but they ask for little in return. I also enjoy helping animals and their owners feel better. Pet owners are happy when th如图所示，四边形ABCD内接于⊙O，∠BOD=140°，则∠BCD等于（ ）A．140°B．110°C．70°D．20°