确诊脓肿形成的最可靠依据是

A．血培养
B．穿刺
C．触诊
D．测体温
E．透视

The inside light in an inflatable liferaft is turned on（）.

A.automatically as the liferaft inflates

B.with a switch near the boarding handle

C.at night because the light has a photosensitive switch

D.by screwing the bulb in after the raft is inflated