你能够利用一张白纸和一把刻度尺测出一个凸透镜的焦距吗？请简述测量步骤．

已知数列$\left\{a_n\right\}$的前n项和为$S_n$，且$a_1=1,S_n=n^2{a}_n\left(n\in N^{*}\right)$，可归纳猜想出$S_n$的表达式为(  )

文题一：请把“就这样                          长大（慢慢地、幸福地、快乐地、奇妙地……）”这个题目补充完整后写一篇作文。要写出亲身经历，写出自己真实的心理感受。

文题二：请以“发生在教室里的故事”为题目写一篇作文。

要求：（1）字数不少于600字。（2）除诗歌、戏剧外，文体不限

阅读理解
The booking notes of the play “Sherlock”
Price :$10
BOOKING
There are four easy ways to book seats for the performance:
——in person
The Box Office is open from Monday to Saturday, 10 am—8pm
——by telephone
Ring 01324976 to reserve your tickets or to pay by credit card (Visa and MasterCard).
——by post
Simply complete the booking form and return it to Box Office.
——online
Complete the on-line booking form at www. Satanfiedtheatre.com.
DISCOUNTS:
Saver: $2 off any seat booked any time in advance for performances from Monday to Thursday. Savers are available for children up to16 years old, over 60s and full-time students.
Supersavers: half-price seats are available for people with disabilities and one companion. It is advisable to book in advance. There is a maximum of eight wheelchair spaces available and one wheelchair space will be held until an hour before the show.
Standby: best available seats are on sale for $6 from one hour before the performance for people eligible for Saver and Supersaver discounts and thirty minutes before for all other customers.
Group Booking: there is a ten percent discount for parties of twelve or more.
School: school parties of ten or more can book $6 standby tickets and will get every tenth ticket free.
Please note: we are unable to exchange tickets or refund money unless a performance is cancelled due to unforeseen circumstances.

今年参加全国人民代表大会的代表中，少数民族代表406名，占代表总数的13.5%。各少数民族都有本民族的代表。这体现了（   ）