选择素分子识别的配体是()
A.CD15s(sLex)
B.CD21
C.CD31
D.CD44
E.钙粘蛋白
参考答案:A
鞭虫卵的典型特点是( )
A.呈纺锤形 B.黄褐色C.卵壳较厚 D.两端各有一个透明的盖塞
A.The influence of old people in the U.S.
B.Citizens and life in the U. S.
C.Changes in American families.
D.The old people in the U. S.