The hat is ___________ small for me. [ ]
A. to
B. too
C. two
答案:B
一母亲为21/21易位携带者,其下一代罹患唐氏综合征的概率是()
A.1%
B.10%
C.4%
D.2%~4%
E.100%
房间隔缺损时,不会增大的是
A.左房
B.左室
C.右房
D.右室
E.肺动脉