Just a few minutes every day, _______ you could have shining floors and furniture with this new cleaner.

A．but

B．and

C．or

D．so

边缘性骨髓炎最常见病因（）

A.下磨牙根尖感染

B.上磨牙根尖感染

C.颌下间隙感染

D.智齿冠周炎

E.医源性