题目

What do you want to be when you grow up? A teacher? A doctor? How about an ice-cream taster? Yes, there really is a job where you can get paid to taste ice cream. Just ask John Harrison, an “Official Taste Tester” for the past 21 years. Testing helps manufacturers(制造商) to be sure of a product’s quality. During his career Harrison has been responsible for approving large quantities of the sweet ice cream— as well as for developing over 75 flavors . Some people think that it would be easy to do this job; after all, you just have to like ice cream, right? No— there’s more to the正方形网格中，∠AOB如图放置，则cos∠AOB的值为（ ）A．B．C．D．2