巷道周壁沉积煤尘是产生煤尘爆炸的直接原因，因此沉积煤尘是造成煤尘爆炸的最大隐患。
参考答案：错
—Tim ______ the science test last weekend. What about you, Peter?
—I ______ English. [ ]
A. studied; studied
B. studied for; studied
C. studied for; studied for
连结员和站务人员遇特殊情况都可担任调车指挥工作。
