His brother is naughty, ________ he is quite shy.
A.when
B.while
C.for
D.though.
答案:B
诊断黄体萎缩不全功血的可靠依据是
A.孕激素分泌量少
B.月经第5天内膜有分泌反应
C.雌激素分泌过多
D.宫颈粘液呈椭圆体型
E.基础体温呈双相
简述组织结构的特征。