增生性龈炎的直接病因是

A．牙菌斑
B．服用药物
C．内分泌导致的激素变化
D．遗传因素
E．全身疾病

It is said that his missing paintings were ______the possession of Russicans and they were valued____500,000$

A．in ; to

B．in; at

C．under; at

D．to; for