越古老的地层里,成为化石的生物越( )
A.复杂、高等
B.简单、低等
C.复杂、低等
D.简单、高等
答案:B
下列哪一种激素是升高血糖浓度最重要的激素()
A.生长激素
B.胰岛素
C.肾上腺素
D.胰高血糖素
E.肾上腺皮质激素
Mrs Chen ________ the shopping centre for an hour. She is buying a dress now.
A.has got to
B.has been to
C.has came into
D.has been in