题目

Millions of people visit Yosemite National Park every year to see the tall waterfalls and mountains. These mountains are a splendid sight when viewed from the valley floor. Lots of stores, hotels, and restaurants are needed to handle the crowds. Also, water, roads, and other service systems are part of the infrastructure（基础设施）that must be maintained.     Unfortunately, these systems are starting to break down. It is not just in Yosemite but in national parks around the nation.     Yosemite is thirty years old according to Dennis Galvin, a National Park Service worker.     “山坡坡栽树涯畔畔青，黄土高原有了好风景，狂沙那个不起尘少见，林果绕村绿满山”，歌曲展示了黄土高原人民改造大自然的结果。下列有关黄土高原的治理措施不可取的是A、坡脚建挡土坝、护坡 B、退耕还林、还草 C、开荒种田，增加耕地面积 D、缓坡地修建梯田