将一个边长为10cm正方形,沿粗黑实线剪下4个边长为____ cm的小正方形,拼成一个大正方形作为直四棱柱的一个底面;余下部分按虚线折叠成一个无盖直四棱柱;最后把两部分拼在一起,组成一个完整的直四棱柱,它的表面积等于原正方形的面积.
We want to know he will come back, as we are worried about his safety.