如图为一款3D眼镜，感受3D影院和3D游戏。某企业要开发这一装置，会受到主客观条件的限制，以下不属于限制条件的是（   ）

完形填空   

There was a bridge crossing a big river from west to east. It1a man five minutes 2 it. There was a pavilion(凉亭)3the middle of the bridge with a soldier4. He came out5three minutes.6he saw somebody crossing the bridge, he would tell him to go7, not permitting(限制)him to cross. A clever man thought of a8idea, and crossed the9at last. What10did the clever man think of to cross the bridge?

在5×5网格中，∠α的位置如图所示，则tanα的值是（   ）

The bridge is ________meters long.  

 2014年诺贝尔物理学奖获得者的主要贡献是发现蓝光 LED. 二极管的两根引线有正、负极之分,二极管导通时,其电阻为零.如图l3电路, R消耗的功率为P₁;现将二极管正、负极对调再接入电路的相同位置, R消耗的LED功率为P₂.已知P₁:P₂=16:1,则灯泡电阻R_L(不随温度变化)与 R 的比值R_L:R=____,灯泡工作时消耗的功率等于 P₁的____倍 (可用分数表示).