——Are you worried about the coming exam?——No, I think the more _________you are, _________mistakes you'll make.
A：careful; the less
B：carefully; the fewer
C：carefully; the least
D：careful; the fewer
用显微镜对光时，如果视野内光线较强，应选择下列哪项来进行调节？（ ）
①较大的光圈 ②较小的光圈 ③反光镜的平面 ④反光镜的凹面．
中国秦朝因长城和兵马俑而名满世界，这些举世闻名的工程得以完成的基本条件是
