如图,△ABC为⊙O的内接三角形,O为圆心,OD⊥AB,垂足为D,OE⊥AC,垂足为E,若DE=3,则BC=____.
In many parts of China, people _______ the custom of "biting the spring" on the first day of Start of Spring, with spring pancakes and spring rolls eaten.
遭遇险情,错误的做法比灾难本身更可怕。下列逃生技巧中不可取的是( )
植物体的所有活细胞都能进行光合作用和呼吸作用。( )