题目

阅读下列短文，从每题所给的A、B、C和D四个选项中，选出最佳选项。In Iceland, these green houses melt into the natural landscape, a technique that first appeared with the arrival of British settlers during the 9th through 11th centuries. Unlike their previous warm and wet climate, wood was rare and slow to regenerate. Turf (草皮) became their first pick to make shelters.Across Europe, turf bricks—widely available—were cut from local bogs (沼泽) and transported for use at higher lands. The turf was then laid over a wooden structure to form walls and a thick roofi是虚数单位，计算="                                                   " （   ）A．1B．-1C．iD．-i