题目

The idea of “Sunshine Sport”makes it possible for kids to do _____about sports as long as one hour every day. A pleasant something   B anything pleasant  C nothing pleasant  D something pleasant 答案：D如图，在△ABC中，点D，E分别是边AB，AC的中点，AF⊥BC，垂足为点F，∠ADE=30°，DF=4，则BF的长为（ ）A．4 B．8 C．2 D．4