已知数列$\left\{a_n\right\}$中，$a_1=3,a_n-a_{n+1}-2=0$，则$\left\{a_n\right\}$的通项公式为（　　）

看图，补全句子。

The skirt is too big.

用括号内所给动词的适当形式填空。
____ In the past three years, my home town ______________(change) a lot. already.
____ It's hard to say what ____________ (happen) in 100 years in our country.
____ They_______________(not travel)to Shanghai next week, are they?
____ The students________(chat) from 6 to7 yesterday evening.
____ When I got to the station yesterday morning, my friends _______(wait ) for me at the entrance.
____ If it__________ (not rain) tomorrow, we'll go hiking.
____ He____________ (not write) a letter to his mother yet. He has to do that soon. His mother misses him very much.
____ Would you please__________(not make) such a big noise. The baby is sleeping.
____ It's a long time since we ________(meet) last time, isn't it?
____ ——How many times _______the girl __________(forget) to take the keys to her home?——At least three times.
____ You must spend as much time as you can ________  (practise) playing the piano.
____ They_______(live) in Wuxi since they were born.

若$\sqrt{2^{m+n-2}}$和$\sqrt{3^{3m-2n+2}}$都是最简二次根式，则m=____ n=____