Welcome to the House of Noodles! In our restaurant, we have some great specials. We have different kinds of noodles like mutton noodles and beef noodles. There are some delicious vegetables in the noodles. What size bowl of noodles would you like? A large bowl of beef noodles is only eight yuan. For mutton noodles, a small bowl is five yuan, a medium one is seven yuan and for a large one, it is just ten yuan. You can also order our cabbage and egg noodles for just four yuan. And we have free green tea for you every day. All our noodles are good and at a good price!

阅读〔快活三〕和〔鲍老儿〕前面的大段独白，下面理解不正确的一项是：（　）

理由如下：

∵∠1=∠2（已知），

且∠1=∠CGD（____）

∴∠2=∠CGD（等量代换）

∴CE∥BF（____）

∴∠____ =∠BFD（____）

又∵∠B=∠C（已  知）

∴____（等量代换）

∴AB∥CD（____）

“$a>0$”是“方程$y^2=ax$表示的曲线为抛物线”的（   ）条件