题型:问答题 论述题 I’d like to buy a present for my father’s birthday, ________at a proper price but of great use.A.oneB.itC.thatD.this 查看答案
题型:问答题 论述题 核型为47,XX,21的唐氏综合征(又称21-三体)儿,其双亲核型正常,则发病原因是().A.多基因病B.常染色体显性遗传C.新发生的畸变D.常染色体隐性遗传E.X连锁隐性遗传 查看答案