图为“哈尔滨、北京、武汉、广州四城市气温和降水月分配图”，看图回答问题：

在区间-$\frac{\mathrm{\pi }}{2}$,$\frac{\mathrm{\pi }}{2}$上随机取一个数x，cosx的值不小于$\frac{1}{2}$的概率为（　　）

用方框中所给单词的适当形式填空，使短文通顺、正确、连贯（每个单词限用一次）

To: Christin foo@hotmail.com

Date: 23^rd March
Subject: The Riding for the Disabled Association
Hi Christine,
Sorry I haven't emailed lately —I've been very busy since becoming a volunteer for the Riding for the Disabled Association.
Every Saturday, I help to get the horses ____  for the disabled(残疾) riders. Many more disabled people want to ride ____ than you'd imagine. It's a disadvantage that I don't know how to ride —I'd love to got on long rides with the riders— but I'll learn soon ____ . Right now, I'm just happy to be able to lead the horses around for the disabled riders.
    I'm____  helping to organize a sale, which will be ____  next month. It's a lot more work than helping the disabled. I need to collect second-hand things to sell at the sale. There are ____  things available(获得的) than I thought, but I'm sure we'll have enough____  next month.
     I hope the sale raises more money than last month's walk. It was rainy, so too few people took part in the event. Last week, we held an auction(拍卖). The auction took much less ____ to organize than the walk. ____ , for some reason, people offered too little money for the things, so we didn't raise enough money.
     I'm ____ you some pictures in the letter, as well as a speech I gave last week.

甲坐在人民大会堂台前60 m处听报告，乙坐在家里离电视机5 m处听电视转播，已知乙所在处与人民大会堂相距1 000 km，不考虑其他因素，则(空气中声速为340 m/s)(　　)

已知函数f（x）的定义域为R，若存在常数m＞0，对任意x∈R，有|f（x）|≤m|x|，则称函数f（x）为F﹣函数．给出下列函数：

①f（x）=x²；

②$f\left(x\right)=\frac{x}{x^2+1}$；

③f（x）=2^x；

④f（x）=sin2x．

其中是F﹣函数的序号为（　　）