Those boys _____ many times not to go on line, but it doesn’t make any difference.

A．have told

B．told

C．have been told

D．were being told

监测麦康凯琼脂培养基常见的质控菌株是（）.

A.福氏志贺菌ATCC12022

B.大肠埃希菌ATCC25922

C.化脓性链球菌ATCC19615

D.肺炎链球菌ATCC6305

E.脆弱类杆菌ATCC25285