胚胎第5周时主要造血器官是
A.卵黄囊B.胆囊C.淋巴管D.肝脾E.骨髓
参考答案:A
解析:胎儿血循环约于受精后3周末建立,其红细胞主要来自卵黄囊。
It's not very important to give them ______ advice. [ ]
A. too much
B. much too
C. too many
D. many too
明初加强专制统治的措施中,与后来宦官专权有直接关系的是( )。
A.废除丞相
B.设立厂卫特务机构
C.八股取土
D.地方设“三司”