We often talk a great deal about English language teaching, ______ that it is the learning that really matters.[ ]

A. having forgotten

B. forgotten    

C. forgetting     

D. to have forgotten

下列静脉属门静脉系统的是()

A．中央静脉

B．肠系膜上静脉

C．肠系膜下静脉

D．直肠上静脉

E．直肠下静脉