超声诊断早期妊娠,首先见到的是
A.胎囊B.胎头C.四腔心D.受精卵E.肾脏
参考答案:A
解析:超声诊断早期妊娠,首先见到的是胎囊。停经5~6周即可显示宫内的胎囊回声。
化简求值:已知|a-4|+(b+1)2=0,求5ab2-[2a2b-(4ab2-2a2b)]+4a2b的值.
. They got married in 2001 and three years later they ________ their child.
A.have
B.had
C.had had
D.will have