During exams, students concentrate hard on answering the questions.考试期间，同学们集中精力回答问题。focus v.集中(于某事物)；将(注意力等)集中于……(后接on，宾语一般不是具体的东西)。

Please focus your minds on the following problem.请集中考虑以下问题。13、confinement, limitation, restraint"限制，局限"confinement n.限制，囚禁(于某地或某种境地)。

The prisoner was sentenced to three months’ solitary confinement.那犯人被判处单独监禁三个月。limitation n.限制，局限；(能力的)缺点，弱点。

That employee has limitations on what work he can do.那个雇员能做的工作有限。restraint n.克制，抑制；约束措施。

Even though the mother was very angry, she acted with restraint and didn’t yell at her child.即使母亲很生气，她仍克制自己没有向孩子大吼。14、considerable, considerate这是一对形近易混的形容词。considerable a.相当大的，相当多的；值得考虑的。

That family owns a considerable amount of land.那个家族拥有大量的土地。considerate a.考虑周到的，体贴的，后面常跟of结构。

He is always considerate of others; he is kind and sympathetic.他总是很体谅别人，他很慈善并且富有同情心。15、conserve, preserve, reserve都有"保存"的意思。conserve v.保存，保藏，保护(强调节约)。

In winter, some people conserve energy by lowing the heat at night.冬天，为节约能源有些人在夜里把暖气调小。preserve v.保护；维持；保养；防止(食物)腐败(使不受破坏)。

The government preserves the rights of the individual person.政府保护个人的权利不受侵犯。reserve v.保留，储备(强调为某一特殊目的)；订(座位)，预定。

We are reserving these seats for my parents.我们把这些座位留给我的父母。54、continual, continuous, constant, incessant

这一组形容词都有"不断的，不停的"的意思。continual a.连续不断的；频繁的。表示时断时续的发生。

That dog’s barking is a continual annoyance.那条狗不停地叫，真是烦死人了。continuous a.不停的，连续不断的，强调中间不停顿。

Our homes and offices need a continuous supply of electricity.我们的家庭以及办公室需要不间断的供电。constant a.不断的，经常的，强调始终如一地经常出现。

Everything in the universe is in constant motion.宇宙中的万物都在不断地运动。incessant a.不停的，持续不断的，强调令人厌烦地重复出现，中间有可能有停顿。

Incessant noise makes me appreciate silence.持续不断的噪声骚扰使我喜欢安静的环境。16、convert, invert, revert, transform都有"转变"的意思。convert v.转变，变换，含有"使某人改变观点"的意思。He wants to convert to Catholicism.他要皈依天主教。invert v.使颠倒，使倒转，使反向。常常表示位置、顺序、方向等的颠倒。

The baby inverted the cup and spilled her orange juice.婴儿把杯子打翻，弄洒了里面的橙汁。revert v.归还，恢复原状。指回到原来的状态或情形。

John gave his brother a house, and when his brother died, ownership reverted back to John.约翰送给他的哥哥一所房子，当他的哥哥去世后，房子的所有权重新归于约翰。transform v.改变，转变，指形状、颜色、大小、性质等的改变。

A little paint will soon transform the old house.刷一点油漆很快就会使这所旧房子大为改观。17、credible, credulous, plausible都有"可信的"意思。credible a.可信的，可靠的。

That the student told the teacher a credible story that she missed classes because she was sick.那个学生跟老师讲了实情，她没来上课是因为她病了。credulous a.轻信的，易于相信的。

She was credulous when she listened to the salesman and bought the car for too much money.她很容易轻信别人，竟然听信那个销售员的话以高价买了那辆车。plausible a.似乎有理的(可信的)。常带有怀疑的意思。

Even though it is a plausible explanation, I am not completely convinced.虽然这个解释合理，但仍不可能使我完全相信。18、decline, refuse, reject, deny都有"拒绝"的意思。decline v.婉言拒绝，谢绝，相当于refuse politely，主要用于拒绝有关社交活动的邀请或要求帮助的请求，后接名词或动词不定式，主语只能是人。

I invited her to join us, but she declined.我邀请她和我们在一起，可是她婉言谢绝了。refuse v.是比较普通的用词，表示"拒绝"，含有非常坚决地、不客气地拒绝的意思。reject v.抛弃，不采纳，主语可以是人或物，后接名词，不能接动词不定式。

He asked her to go to the movies three times, and each time she rejected him.他三次约她去看电影，但每一次都被拒绝。deny v.否认，否定，其后可接名词，代词或that从句。

The defendant denied the accusations made against him in court.被告在法庭上否认了对他的指控。