问题 问答题

有两根长短、粗细、外表颜色都差不多的金属棒,一根是铝的,一根是铁的.请你根据它们的物理、化学性质,用尽可能多的各种不同方法把它们区分开来,并简述所用方法要点.

答案

用天平称量两根金属棒的质量,质量大的是铁棒,质量小的是铝棒.根据金属铝的密度比金属铁小,可以区分铝和铁.

用两根金属棒刻画铜片,痕迹明显的是铁棒,痕迹不明显的是铝棒.根据铁的硬度比铝大,可以区分铝和铁.

用磁铁靠近两根金属棒,能被磁铁吸引的是铁棒,不能被磁铁吸引的是铝棒.

根据铁能被磁铁吸引,可以区分铁和铝.

把两根金属棒分别放入质量分数和质量都相同的稀硫酸中,反应较快的是铝棒,反应较慢的是铁棒.

填空题
阅读理解

When it comes to President Obama, most of his personal business is already known by the public. Personal information about his children, Malia and Sasha, however, has been kept a little more under wraps.

The New York Times recently released a list of rules that Michelle Obama has mentioned over the years that Malia and Sasha must follow during their time in the White House, as well as in general. See how the first family educates their children:

The girls must write reports about what they’ve seen on their trips, even if it’s not required by their school.

Malia may use her cell phone only on the weekends, and she and her sister cannot watch television or use a computer for anything but homework during the week.

Malia and Sasha have to play two sports: one they choose and one selected by their mother.

Malia must learn to do laundry(洗衣服) before she leaves for college.

The girls have to eat their vegetables, and if they say they are not hungry, they cannot ask for cookies or chips later.

While these might be shocking to some, Michelle said, “They’re not little princess. It’s just basic rules, boundaries, and expectations that we would have normally.”

Michelle also mentions another set of rules:

The girls must do their chores(家务), though the White House has a large staff. Malia and Sasha have chores of their own.

They must play a team sport, because it’s about learning how to play on a team, how to lose and how to win gracefully.

It sounds like Michelle and Barack want the best for their kids and to make them as well-rounded as possible. What are your thoughts on the Obama family rules?  

小题1:What’s the passage mainly about?

A.The first family daily life.

B.The first family rules.

C.How to be good parents.

D.How to be good students.小题2:What do the underlined words “under wraps” probably mean?

A.Attractive.

B.Calm.

C.Secret.

D.Public小题3:What has to be followed after the girls’ every trip?

A.Emails.

B.Photos.

C.Homework.

D.Reports.小题4:Which of the following is the exception for the girls?

A.To use cell phone freely.

B.To play two sports.

C.To learn to do laundry.

D.To eat their vegetables.小题5:Which of the following is NOT True according to the passage?

A.The girls have to obey the rules only when they live in the White House.

B.The girls must do their chores though there might be lots of help around.

C.The girls must play a team sport to gain team spirit by working together.

D.The parents want to make the girls grow healthily as common children.