题目

People have strange ideas about food. For example, the tomato is a kind of very delicious vegetable. It is one of useful plants that can be prepared in many ways. It has rich nutrition and vitamin in it. But in the 18th century, Americans never ate tomatoes. They grew them in their gardens because tomato plants are so pretty. But they thought the vegetable was poisonous (有毒的). They called tomatoes “poison apples.” President Thomas Jefferson, however, knew that tomatoes were good to eat. He was a learned man. He had been to Paris, where he learned to love the taste of tomatoes. He gre如图所示，∠ABC=∠BCD，BE、CF分别平分∠ABC和∠BCD，请你说出BE与CF的位置关系，并说出你的理由．