患者，男，17岁，间歇性发作双足红肿热痛二年，每于秋冬季发作，此次再发求治。疼痛呈搏动性，不能入睡，置双足于被子外面枕上可觉疼痛稍轻，白天喜欢将双足浸泡在凉水中，站立加重。检体：双足踝以下红肿，皮温高，双足背动脉宏大。

诊断性依据是什么？

They considered ___ a computer, which was considered ___ a great help in their work.

A．to buy; to be

B．buying; being

C．to buy; being

D．buying; to be