DNA是地球上所有生命的基础，它有着像螺旋式楼梯一样的双螺旋结构。

DNA is the basis of all life on earth. It has a double helixstructure， like a spiral staircase.//

youdao

DNA是地球上所有生命的基础，它有着像螺旋式楼梯一样的双螺旋结构。

DNA is the basis of all life on earth. It has a double helixstructure， like a spiral staircase.//

youdao