如图所示，电阻R₁标着“10 1A”，R₂标着“5  1.5A”，闭合开关S后为保证R₁、R₂均不损坏，则a、b之间允许加的电源电压不得超过（）

中考临近，妈妈禁止小华上网玩游戏，小华为此大发脾气。对小华行为认识正确的是（）
①小华应该正确对待妈妈的教育          ②小华合理发泄了自己的情绪
③小华应尊重父母，克服消极的逆反心理  ④妈妈应该积极地与小华沟通 

方程组x$\left(\begin{array}{c}1\\ 1\end{array}\right)$+y$\left(\begin{array}{c}2\\ -1\end{array}\right)$=$\left(\begin{array}{c}5\\ 2\end{array}\right)$的解是____ ．

福州近期空气质量指数（AQI）分别为：78，80，79，79，81，78，80，80，这些组数据的中位数是（　　）

Events

Long March exhibit

    The Shanghai History Museum is putting on an exhibition to mark the 60^th anniversary of the Long March. On show are more than 220 photos and 40 items that explain with pictures how the communist Red Army drew back from its besieged(被围困的) bases in Jiangxi Province and fought its way to northern Shanxi province in the mid-1930s. Explanations are all in Chinese. The show will end on November 20.

Time: 10:00 am—4:00 pm.

Address: 1286 Hongqiao Road

Admission: 8 Yuan for Chinese/ 15 Yuan for foreigners

Thai elephants

    Eight elephants from Thailand are entertaining visitors at Changfeng Park by riding bikes, playing basketball, balancing on a beam, dancing and blowing a mouth-organ. People are encouraged to have a tug-of-war(拔河比赛) with the animals or lie on the ground and have the elephants walk over them. The elephants give three shows a day at 9:30 am, 3:30 pm and 8:00 pm and there is an additional show at 1:30 pm at weekends. The show will end on November 15.

Address: 189 Daduhe Road

Admission: 30-40 Yuan

Dancing dolphins

    Dolphins jumping from the water to touch a ball, swaying their bodies to music, kissing people and doing math by tapping their tails have made the dolphinarium in Peace Park an attraction for children. Seals and sea lions also perform.

Hours: 10:30 am, 4:00 pm, and 7:30 pm

Admission: 20 Yuan for adults and 10 Yuan for children.