题目

阅读理解 People have been enjoying the benefits of cycling(骑自行车) in Amsterdam(阿姆斯特丹) for years. It is a good city for cycling because it is flat and thereare plenty of places for bicycle parking. Today some people call Amsterdam Cityof Bicycles because of the convenience for bicycles there. In the 1960s, a group of cycling fans had anidea. They believed that it would be better for everybody if cars weren't allowedin the city centre and only bicycles were. They were hopeful that this would helpto save energy, reduce pollution and provide free public transport. The group pa18．乙地所在地形区春季影响农作物生长的突出自然灾害是（　　）A．虫害B．冻害C．滑坡D．洪水