All passengers _____ are expected to fasten the seat belts when the plane takes off and lands. [ ]

A. on aboard

B. on board

C. on the board

D. on boards

设有二维数组A[0..9,0..19]，其每个元素占两个字节，数组按列优先顺序存储，第一个元素的存储地址为100，那么元素A[6,6]的存储地址为______。