如图所示，OD是∠BOC的平分线，OE是∠AOC的平分线，找出图中互补的角、互余的角．

    He wishes the holiday season would end already. His back aches, his red suit feels like a spacesuit, his cheeks have gone tight from smiling for 12 hours—and still the kids keep coming and coming, like ants at a picnic. As Christmas becomes more commercialized (商业化) across the U. S. and Canada, so must Santa Claus. As the holiday begins earlier each year, so must its spokesmen.

    The questions from children these days are harder than ever. Now, with thousands of children expecting a father or mother serving in Iraq or Afghanistan, the questions are as heart­breaking as they are unanswerable. For example, “Can you please bring Daddy home from the war in time for Christmas morning？”

    Santa Claus; also have a pretty good chance of getting sued (指控). A professional Santa Claus in Canada told a story: A Santa had a girl on his knee, and he commented, “You have nice eyes and nice hair.” The girl later said it was sexual harassment (骚扰). When a Santa feels anxious, he often shows it in the same ways ordinary people do. The Santa Claus were always seen to hang around at the dinner table when the show ended. Many of them just sleep in bed for several days and don't see other children again.

如图所示，李宁同学在张老师指导下做“探究凸透镜成像规律”的实验．

（Ⅰ）求数列 $\left\{a_n\right\}$ 的通项公式；

（Ⅱ）设 $b_n=\frac{n}{a_n}$ ， $S_n$ 是数列 $\left\{b_n\right\}$ 的前 $n$ 项和，对任意正整数 $n$ ，不等式 $S_n+\frac{n}{2^{n+1}}>{\left(-1\right)}^n\cdot a$ 恒成立，求实数 $a$ 的取值范围．