题目

There are_____things more important to society than educating children and providing healthcare to families．       A．few                     B．a few                   C．more                     D．many 答案：A光线弱的时候，应该使用显微镜的(    )A．大光圈和平面镜B．大光圈和凹面镜C．小光圈和平面镜D．小光圈和凹面镜