A：在人群中随机抽样调查并统计
B：先调查基因型频率，再确定遗传方式
C：通常建立系谱图必需的信息不包括遗传病是显性还是隐性
D：先调查该基因的频率，再计算出发病率
During the summer holiday，Alice had a nice trip．First she took a plane from Changchun to Beijing．She went to the Great Wall．She was very tired．But she was happy．She likes Beijing very much．Then she went to London by plane．She visited Big Ben，the clock tower．There were many museums in London．She learnt a lot there．People in London love eating fish and chips．She stayed in London for 5 days．Then she took a plane to Shanghai．Then she went to Changchun by plane．
根据短文，判断正误。
要求：①文体不限，诗歌除外。②不少于500字。③文中不能出现真实的人名、校名、地名。
函数y=a﹣x和函数y=loga（﹣x）（a＞0，且a≠0）的图象画在同一个坐标系中，得到的图象只可能是下面四个图象中的（ ）
