为诊断遗传性疾病或确定胎儿性别行羊膜腔穿刺应选择的时间是()
A.妊娠8~10周
B.妊娠10~16周
C.妊娠16~20周
D.妊娠20~24周
E.不受孕周限制
参考答案:C
(3a+b)(a-b)
—Have you ever been to Qufu?
—Yes. I went there last year. It’s a very _______ place.
A.educational
B.dangerous
C.difficult
D.delicious