阅读下列短文，从每题所给的A、B、C和D项中，选出最佳选项。

    Hannibal was a general from Carthage, a city on the northern coast of Africa. He thought the ancient Romans and won great battles at a time when the Romans were the most powerful people in the world. His army was small, but it was made up of soldiers from many countries that didn’t want to be ruled by the Romans.

    Before Hannibal could fight the Romans always had thought would protect them from enemy armies. When winter came, the Romans did not think Hannibal could possibly cross the mountains. Hannibal surprised them. With some of his soldiers riding huge strong elephants—where no elephants had to walk slowly without resting through the mountain snow-storms and howling(怒号)winds. The enemies rolled rocks down to try to stop them. Even raging rivers couldn’t stop them. Hannibal’s soldiers built rafts(木排)strong enough to carry the elephants across. At last, half of them never reached the end of their journey. But the other half of the army and some of the elephants did finish the journey.

阅读材料，回答下列问题：

进入初中后，内向文静的小花开始渐渐关注自己。她发现自己的身高比同桌矮，性格不如同桌活泼开朗，家庭经济条件也没有同桌优越。虽然学习成绩在班中名列前茅，但每次考试总比不上同桌，在同桌面前，她觉得低人一等。因此，小花非常烦恼。她变得越来越内向和孤僻。

如图，在平行四边形ABCD中，AD=2AB，F是AD的中点，作CE⊥AB，垂足E在线段AB上，连接EF、CF，则下列结论中一定成立的是（　　）

①∠DCF=$\frac{1}{2}$∠BCD；②EF=CF；③S_△BEC=2S_△CEF；④∠DFE=3∠AEF．