题目

远望巍巍塔七层，红灯点点倍增加．有灯三百八十一，请问尖层几盏灯？ 答案：解：假设尖层的红灯有x盏，由题意得：x+2x+4x+8x+16x+32x+64x=381127x=381x=3答：尖层3盏灯．The teacher often tells us ________ much time________TV.A.not to spend; watch B.not to spend; watchingC.don’t spend; watching D.to not spend; watch