设y=xex，则∫y’dx=______。
参考答案：xex+C
属于孕激素生理作用的是：
A．使增生期子宫内膜转化为分泌期
B．促使子宫发育及肌层变厚
C．使乳腺腺管增生
D．使 * * 上皮细胞增生、角化
E．促使钠、水潴留
Some scientists think that it may take ______ years to make robots look like people, and do the same things as us.
A．hundreds of
B．two hundreds of
C．two hundreds
D． hundreds
