Has your sister finished her homework _____?[ ]
A. yet
B. just
C. still
D. already
答案:A
沉井在施工中会出现哪些问题,应如何处理?
家族性多发性结肠息肉是一种显性遗传病。如果双亲中一个是基因组成为Ee的患者,另一个表现正常,那么他们子女发病的概率是 [ ]
A.20%
B.50%
C.75%
D.100%