题目

My grandmother often said to me, “You can count the number of your true friends on the fingers of one hand.” For a long time I thought this was true. However, I’ve now discovered my grandmother was only half right. Maybe we do only make a few “best” friends in our lifetime, but those aren’t the only people that we can call friends. There are many different types. Let me tell you about a few of them. One type of friends is the type I call the “football mom friend”. My neighbor Sally is a good example. We both have kids who play football in a football club, and someone has用含同位素14C的CO2来追踪光合作用碳原子的转移，最可能的途径是（　） A．14CO2→叶绿素→ADP　　　　  B．14CO2→ADP→ATP C．14CO2→三碳化合物→葡萄糖　　　　　　　　    D．14CO2→酒精（或乳酸）→葡萄糖