A:four times the size of
B:the size four times of
C:four times the size a
D:four times as the size of
Today is Saturday. The weather is warm and sunny. Bob and Jack go to the park. There are many people there. The girl under a big tree is reading a book. Two boys are playing football on the grass. The girl in a red dress is riding a bike. Two women are talking. The man beside these women is playing with a baby. Bob and Jack are beside the river. They are sitting on the chair and drawing pictures.
若(4k+1)•180°<α<(4k+1)•180°+60°(k∈Z),则α所在象限为( )
园艺师能将一株单颜色的野菊花,培育成具有多种颜色的“塔菊”,采用的是下列哪一项技术( )