题目

(2020·惠州市高三第一次调研考试试题)Today, Mount Qomolangma's peak is not a lonely place any more. Over 3,500 people have __1__ (successful) climbed the mountain over the past year. Meanwhile, climbers have complained about __2__ (wait) for hours in the bottlenecks. In fact, the dangerous __3__ (crowd) aren't the only problem. All those climbers need __4__ (bring) a lot of gear (设备), much of which ends up being left on the mountain. It is becoming the world's __5__ (tall) rubbish dump. But the good news is __6__ some mountaineers have started to clean up Qomolangma. 关于下列晶体的模型中，说法不正确的是（　　）A．金刚石中最小的环为六元环B．SiO2中最小的环为六元环C．NaCl晶胞中和Na+距离最近的 Cl-有6个D．石墨是层状结构，最小的环为六元环