题目

Tom won't go to bed until his father ________ back from work. A . will come B . came C . comes D . come 答案：C南京紫金山天文台气象观测环境比建站初期明显恶化的主要原因是 [     ]A．水污染加剧B．光污染加剧C．臭氧层破坏D．酸雨腐蚀增强