下列属于临产的标志的是 （）

A.见红，规律宫缩，胎头下降

B.规律宫缩，破膜，胎头下降

C.见红，破膜，宫口扩张

D.见红，破膜，规律宫缩

E.规律宫缩，胎头下降，宫口扩张

One of the most important things in education is to let students ______ positive emotions and

experience in the process of their learning.     [      ]

A. require          

B. acquire    

C. demand    

D. clarify