问题 选择题

在利用弹簧测力计测量一个物体的重力时,下列说法正确的是(  )

A.弹簧测力计对物体的拉力从本质上是由电磁力引起的

B.物体对弹簧测力计的拉力是由于弹簧的形变产生的

C.物体的重力与弹簧的长度成正比

D.弹簧测力计对物体的拉力就是物体的重力

答案

A、从四种基本作用力角度得知,弹力属于电磁力范畴.而弹簧测力计对物体的拉力就是由弹簧形变而产生的弹力引起的,故A正确;

B、物体对弹簧测力计的拉力是由于物体的形变而产生的,弹簧对物体的拉力是由弹簧的形变而产生的,故B错误;

C、弹簧的拉力与弹簧的伸长量及弹簧的劲度系数成正比.故C错误;

D、当弹簧测力计处于平衡状态时,弹簧测力计对物体的拉力等于物体的重力,而并不是重力.故D错误;

故选:A

单项选择题
阅读理解

Fun is, in fact , a word heard far more frequently in families today than in the past , when “duty”and “responsibility ”were often the words used.Parents today are more youthful in appearance and attitudes. Their clothes and hair-styles are more casual, helping to bridge the divide. Those who are athletically inclined also enjoy Rollerblading, snowboarding, and rock-climbing with their children.

For the past three years, Kathy and Phil Dalby have spent at least one evening a week at a climbing gym with their three children. "It's great to be able to work together," Mrs Dalby says. "We discuss various climbs and where the hard parts are. Sometimes that leads to other Conversations. We're definitely closer."

A popular movement of parent effectiveness training in the 1970s has helped to reshape generational roles. The philosophy encourages children to describe their feelings about various situations. As a result, says Robert Billingham, a family-studies professor at Indiana University, "Parents and children began talking to each other in ways they had not before."

On the plus side, he adds, these conversations made parents realize that children may have important thoughts or feelings that adults need to be aware of.

But Professor Billingham also sees a downside: Many parents started making decisions based on what their child wanted. "The power shifted to children. Parents said, 'I have to focus on making my child happy', as opposed to 'I have to act as a parent most appropriately'."

Other changes are occurring as the ranks of working mothers grow.  Time-short parents encourage children's independence, making them more responsible for themselves. "They'll say, 'We trust you to make the right decisions' (whether they're ready to assume the responsibility or not) ,"says Billingham.

The self-esteem movement of the past quarter-century has also affected the family dynamics (原动力). Some parents worry that if they tell their child no, it will hurt the child's self-esteem.

小题1:What's the trend in parent-child relationship mentioned in the passage?

A.Parents are chasing after fashion and ignoring the feelings of their children.

B.More parents and children are sharing the same enthusiasm for a certain sport.

C.Parents are taking more responsibility and setting more limits for their children.

D.The generation gap is narrowing and parents are respecting their children's thoughts more.小题2:Which of the following has NOT contributed to the change in the parent-child relationship?

A.Younger parents.

B.Parent effectiveness training.

C.More working mothers.

D.The self-esteem movement.小题3:What's the best title for the text?

A.Parents and Children as Friends.

B.Parents and Professors as Debaters.

C.Growing Mutual Understanding.

D.Disappearing Responsibility.