题目

— The centre is doing a lot to provide good education for the left-behind children.       — Yeah, but it’s not good enough. They should try ______.A. hard                         B. harder       C. hardest                    D. hardly 答案：B①②③④是有关显微镜操作的几个重要步骤。下图是显微镜下观察到的番茄果肉细胞，要将转换为，正确的操作顺序是①转动细准焦螺旋；②转动转换器；③移动装片；④调节光圈A.①②③④B.③②④①C.④③②①D.②③④①