In fall 2006，the National Basketball Association （NBA）started using basketballs made with synthetic ，or man-made ，material instead of leather（皮革）．They made the change be- cause they wanted every basketball they use to feel and bounce（弹起）the same．Not all leather balls are exactly alike in weight or how they bounce，but the synthetic balls are．

However，some players complained right away that the new balls bounced differently and were actually harder to control than the leather ones．

Physics helped answer questions about why the new balls felt different．For example，the scientists studied friction（摩擦力），which in this case affects the ability of a player to hold onto a ball．"The greater the friction，the better it will stick to his hand，"explains a scientist．

Tests on both wet and dry balls showed that while the synthetic ball was easier to hold onto when dry，it had less friction and became much harder to hold onto when wet．That's because sweat（汗水） stays on the surface of the synthetic balls but gets taken into the leather balls．

The scientists also tested bounce and found that the logo （商标）printed on the new balls made their surface uneven（不平） and caused them to bounce a little strangely com- pared with the leather balls．

In January，the NBA went back to using the leather bails．They aren't perfect，but for now，that's just the way the ball bounces．

1．Why were the synthetic balls expected to be used in NBA according to the text?

       A．Because they are easier to control．           B．Because they waste less material．

       C．Because they look exactly alike．             D．Because they feel and bounce alike．

2．The ball is easier to hold on to_________

A．when friction is greater                    B．when friction is less

C．when it is heavier                         D．when it bounces strangely

3．The synthetic ball bounces differently from the leather one mainly because _________

A．it is wet                                  B．it is dry

C．there's a logo on it                       D．its weight remains the same

4．It can be inferred（推断） from the text that _________．

A．a synthetic ball takes in water faster than a leather ball

B．a leather ball is more difficult to make than a synthetic one

C．a synthetic ball is more expensive than a leather ball

D．a leather ball may increase its weight during a game

5．The underlined word" They" in the last paragraph refers to __________．

A．the synthetic balls                        B．the leather balls

C．the ball players                          D．the scientists

阅读下面短文，根据所读内容，在文章后小题的空格里填入一个最恰当的单词。

注意：每个空格只填一个单词。

Improve Homework Habits

Do you want to make homework simpler? It can be done readily with a little guidance from specialists (专家) in this field. Oxford Learning founder and CEO Dr. Nick Whitehead, said that homework doesn’t always have to be a headache. “Homework might be an unavoidable (不可避免的) part of school, but it doesn’t have to be the boring part. With the right skills in place, students can turn homework from headache-including to trouble-free.” These steps will make an obvious difference.

Use your notebooks

The brain is able to finish great works, but it is not perfect. Students should never rely on (依赖) it to remember all school details. When a teacher assigns homework, students should write the details in their notebooks. Many schools provide notebooks because they are the best organizational tools available.

According to Whitehead, to make them effective, students need to remember to take the notebooks out of their school bags at night, open them up, and read over the night’s list.

Remove distractions (使注意力分散的事物)

Computers on, music on, text messages receiving … this is not multitasking, it’s distracting.

Whitehead says that unless students are doing research, they should turn off all electronics and focus on the task at hand for a set period of time. They’ll find that it is easier to concentrate (全神贯注) and that homework takes less time. He adds that this fact has been confirmed by studies.

Think actively

Getting homework done is the name of the game, but what happens if students are struggling with a question, or can’t work out an answer? When facing difficulties, it is wise for the student to take a small break then return to look at the problem again.

According to Whitehead, students should look up their textbooks and school notes, take a step back to ask what the particular unit is all about, and even move ahead a few questions and see if the next part can help explain a little better. If not, use the Internet.

“Don’t stare at (盯着) the question; ask how this question relates to what is being learned overall.” he says.

Get organized

Homework is as much a part of daily routine as waking up in the morning and going to bed at night, but it’s often the most disorganized part. Whitehead recommends streamlining (使合理化) the process.

“Students should keep all the homework-related things in a bin or a bucket so they don’t waste time searching for pens or rulers.” He also recommends picking the same place to do homework every night, and (when possible) completing homework at the same time each day.