--- Whose comic book is it?  

--- It ________ be Daniel’s. He often shares his comic books with his friends.

A．must

B．can’t

C．mustn’t

D．can

绒毛膜促性腺激素的作用

A．使绒毛发生水泡样变

B．刺激毛发生长发育

C．刺激雌激素分泌

D．促进胎儿生长发育

E．维持妊娠黄体