When travelling in America, we stayed in a quiet hotel, __________.

A．next to it was a thick wood

B．next to which was a thick wood.

C．next to it there was a thick wood

D．next to which a thick wood was

白炽灯灯泡长期使用后，钨丝因升华变细，导致灯丝电阻变　   　，升华后的钨又　　　　（填物态变化名称）使灯泡内壁变黑。