反应Ⅱ的化学方程式为2H₂SO₄ $\underset{\_}{\underset{\_}{太阳能}}$ 2SO₂↑+ O₂↑+ 2H₂O，它由两步反应组成：

第一步：H₂SO₄ $\underset{\_}{\underset{\_}{太阳能}}$ SO₃↑+ H₂O；第二步：SO₃分解。

下列说法中正确的是（   ）

科学家的这种忘我精神（    ）

①体现中华民族精神的核心是艰苦奋斗，它是中华民族的根      ②表明我国国际地位和影响力的提高，有利于实现共同富裕

③充分诠释了敬业乐群、公而忘私的传统美德                              ④说明中华民族精神始终是鼓舞我们战胜困难的力量之源

根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

        Amy, a student in the USA, says that the best diet is to reduce what you eat and doplenty of exercise. Get involved in extra activities and never eat after 9 pmin case what you have eaten turns fat because your body system slows down inthe evening and also while you sleep.____ 

Davidis studying in the USA and he believes that it is a good idea to increase the fiber he eats. ____  Fresh is the best: beans and special fiber materials are excellent choices.

        In the UK, students believe that life as a student can be very difficult. ____ One student, Jennifer, believes that you should eat well, rest well, takevitamins to supplement your diet and you will stay healthy.

        But why are so many young people obsessed with diet and exercise? Mostly because they realize they are putting on weight and they know that obesity can lead toillnesses such as diabetes. Why do they put on weight? ____  They get uplate in the morning, dress quickly, eat quickly and then at lunch they often eat fast food and drink soda, both of which are fattening. They then sit chatting to friends, go back to class and sit listening, and late in the afternoon they leave school, meet friends and sit and chat again. If you arelike most kids, you might have the same experience.

      So,are you a student who is putting on weight? Which of the advice from other students do you think you will act on? ____  So, think about your health and weight. They are both very important for your well－being and your marks at school.

A．Because they lead an unhealthylifestyle and eat the wrong foods.

B．A healthy body means both a healthymind and better marks at school.

C．That means for one whole day they haveeaten fattening foods without exercise.

D．This is found in whole grains, fruitand vegetables which are common and daily foods.

E．Try to go for at least a 10－minute walk after eating, or betterstill, go for a jog or a bicycle ride.

F．You study hard, find yourself understress and then spend a long time out with friends relaxing.

G．Because students who don't exercisetend to put on weight sooner and see a drop in their test scores.

材料一：某校历史兴趣小组根据书中“近代中国社会的发展轨迹像个元宝形，开始是下降，降到谷底，然后上升，升出一片光明……”的描述，绘制了下图。

材料二：“英国军舰公然炮击进攻武汉的北伐军……各帝国主义集结在上海……随时准备进攻北伐军。”