题干

山羊说,42减去26就是我的年龄。山羊多少岁?
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答案(点此获取答案解析)

42-26=16

答:山羊16岁

同类题1

阅读下列短文, 从每题所给的四个选项(A、B、C和D)中选出最佳选项。


    With over 300 years of history, Harvard University, US, welcomed its first-ever Chinese commencement(毕业典礼) speaker. On May 26, He Jiang, a 2016 PhD(博士学位)graduate, gave a speech that stood for the graduate students at commencement. It's one of the highest honors for a Harvard graduate.

    In his speech, he told a story about his childhood. He grew up in a poor village in Hunan. Once a spider bit him on the hand, and his mother had to set his hand on fire to cure him. There were no doctors in the village, and this was the only cure a rural woman knew.

    When he got older, he couldn't help but think about why there wasn't a better cure at that time. And he thought out the answer ---- the unequal distribution of knowledge in the world.

     “Even today we haven't been very successful in bringing knowledge to where it's needed most,” said He. “Even basic life-saving knowledge we can get easily in the modern world is often unavailable in poor areas.” According to the China Children and Teenagers Foundation, there are still around 3 million children in China lacking education, and most of them live in rural areas.

     “One of the biggest problems for rural students is that they lack chances as well as motivation(积极性). It disturbs me that many people in rural areas think studying is useless.” Said He.

    But He Jiang knows how education can change people's lives. “I just hope my experience can give those rural students a bit of encouragement and hope,” said He.

同类题3

铁及碳的化合物在社会生产、生活中有着广泛的应用.请回答下列问题:

(1)磁铁矿是工业上冶炼铁的原料之一.

已知:①Fe3O4(s)+4C(s)⇌3Fe(s)+4CO(g)△H=+646.0kJ•mol1

②C(s)+CO2(g)⇌2CO(g)△H=+172.5kJ•mol1

则Fe3O4(s)+4CO(g)⇌3Fe(s)+4CO2(g)△H=____ .

(2)反应Fe(s)+CO2(g)⇌FeO(s)+CO(g)△H的平衡常数为K,在不同温度下,K值如下:

温度/K

973

1173

1373

1573

K

1.47

2.15

3.36

8.92

①从表中数据可推断,该反应是____ (填“放热”或“吸热”)反应.

②温度为973K时,在某恒容密闭容器中发生上述反应.下列有关说法能说明该反应已达到平衡状态的是____ (填字母).

A.c(CO2)=c(CO)                B.v(CO2)=v(CO)

C.体系压强不变                    D.混合气体中c(CO)不变

(3)如图图1、2表示反应:H2(g)+CO2(g)⇌CO(g)+H2O(g)△H>0有关量与反应时间之间的关系:

①图2中若t1=0.5min,则0~t1时间段内,H2O的平均反应速率v(H2O)=____ mol•L1•s1

②图1中t2时刻改变的条件是____ (任写两种,下同);图2中t2时刻改变的条件是____ .

(4)水煤气中的CO和H2均可作为燃料电池的燃料.若在某燃料电池一极通入CO,另一极通入O2和CO2,熔融碳酸钠作为电解质,工作时负极反应式为____  ;若使用该电池电解熔融Al2O3制取10.8g Al,则理论上需要氧气的体积为____ L

(标准状况下).