They were warried about whether they could get it back.

They were warried about whether they could get it back.
whether可以改成if吗?改成that呢?

whether的“选择”用法
山东平邑一中 马春德 闫志德
请先看下列高考试题：
（1）（NMET 1998）_________ the 2000 Olympic Games will be held in Beijing is not known yet.
A. Whether B. If
C. Whenever D. That（答案为A）
（2000年奥运会是否在北京举行还不得而知.）
（2）（NMET 1996）_______ we”ll go camping tomorrow depends on the weather.
A. If B. Whether
C. That D. Where（答案为B）
（我们明天是否去野营要看天气的好坏.）
（3）（NMET 1998）Shirley was writing a book about China last year, but I don”t know whether she has finished it. （去年雪莉在写一本关于中国的书,但我不知道现在她是否已经写完了.）
（4）（NMET 1999）The price has gone down, but I doubt whether it will remain so. （物价已经降下来了,但我怀疑是否还会这样降下去.）
以上四道高考试题都是对whether“选择”含义的考查.因此,我们不可不对whether的用法加以重视.一般来说,用whether可以构成“whether…or…; whether…or not…；whether or not…；whether…or no…以及whether or no…”等结构,用来指出两种可能性当中的一种.
下面就whether的这一用法作一归纳.
一、作“是……还是……”解时,whether表示一种选择,其后可以跟介词短语或不定式短语.
1. 后跟介词短语.例如：
（1）She made the mistake whether by accident or by design.
不知她是偶然还是故意去犯这个错误的.
（2）Whether through choice or obedience I don”t know, but he certainly did all the work very well.
是出于内心自愿还是奉命行事,这我不晓得,不过他的确是把所有的工作都做好了.
2. 后跟动词不定式短语.例如：
（1）I don”t know whether to accept the offer or refuse it. （= It is doubtful whether to accept the offer or refuse it. ）对这个提议,我不知道是接受好,还是拒绝好.
（2）It is to be decided whether to go or stay here.
是走还是呆在这儿还有待决策.（it作形式主语.）
（3）Will you advise me whether to accept his suggestion （or not）?
向你请教,我是否要接受他的建议?
二、作“是否,会不会”解时,whether可用来引导名词性从句,即主语从句、宾语从句、表语从句和同位语从句.
1. 引导主语从句.引导主语从句时,可用it作形式主语.例如：
（1）Whether they consider this opinion or not is not clear. （= It is not clear whether they consider this opinion or not. ）
他们是否考虑这个意见还不清楚.
（2）Whether we shall be able to come is doubtful. （= It is doubtful whether we shall be able to come. ）我们是否能够来,尚不确定.
2. 引导宾语从句.这时whether可与if换用.例如：
（1）A simple experiment will show whether air has weight or not. （= A simple experiment will show if air has weight. ）一个简单的实验就可以证明空气是否有重量.
（2）I wonder whether we shall be in time for the last bus or （whether we shall）have to walk home.
我不知道我们是否可以赶上最后一班公共汽车,或是只好步行回家.
3. 引导表语从句
The question is whether we have to make a decision at once or not.
问题是我们是否必须马上作出决定.
4. 引导同位语从句.它的前面通常有fact, conclusion, news, problem, question, idea, doubt等名词作同位语结构的中心词.例如：
（1）She has answered the question whether or not this supermarket is the largest one in the region.
她回答了这样一个问题,即该超市在这个地区是不是最大的.
（2）The question whether we ought to call in a specialist was answered by the family doctor.
关于我们是否该请一位专家过来的问题,家庭医生已经作了回答.
三、作“不论……还是……”解时,whether引导让步状语从句.例如：
（1）Whether you can see the moon or not, it is always round.
不论你能否看得见,月亮总是圆的.
（2）You may rely upon my help, whether others help you or not.
不论别人帮不帮你,你都可以依赖我的帮助.
四、whether or no除了能够像whether or not一样引导名词性从句外,还能单独放在句首或句末,作“无论如何”解.这时,它仅起状语作用.例如：
（1）We should complete the general design of the motorcar this year, whether or no.
无论如何,今年我们应该完成这种汽车的总体设计.
（2）You should support your parents, whether or no.
无论如何,你都应该瞻养自己的父母.
THAT用法总结
作者：杨文秀 文章来源：本站原创 点击数：1535 更新时间：2005-12-12
“that”在英文中是一个使用频率很高的单词.它有四种词性,并且句法及语法功能纷繁复杂.同学们如果不能熟练掌握其用法,很可能会形成英语学习的一种障碍,从而影响其学习兴趣和效率.现将that的用法总结归纳如下：
第一、that 用作形容词（后接复数名词时用those）.
它用来指已被提到的人或物；也可表对比,指两个中较远的那个.
What about that book you borrowed from me last month?
请注意,that 有时候在句子中具有喜欢或轻蔑等感情色彩.
that little son of his 他那个小宝贝儿子
That George!乔治那家伙!（含有轻蔑语气）
第二、that 用作代词.
1. that 用作指示代词（复数形式是those）,其指代意义同形容词用法,同时它还可以用作定语从句中的先行词；还可为了避免重复,代替前述名词.
That is what he told me.
What is that (which) you have got in your hand?
The price of rice is higher than that of flour.
2. that 用作关系代词,引导限制性定语从句.先行词可人可物,用法相当于who或which.（但是在下列情况下多用that：先行词既有人又有物时；先行词有形容词最高级、序数词、不定代词、very,only等修饰时；先行词是不定代词时）
He talked about the teachers and schools that he had visited.
I think it one of the most wonderful films that the film company has ever produced.
She has little information that is useful for our research.
Is there anything that I can do for you?
请注意,that 在定语从句中作宾语时通常可省略.
The books (that) I sent you will help you in your studies.
第三、that 用作连词,引导名词性从句,状语从句和强调句.
1. that名词性从句.
①引导宾语从句.及物动词后的引导词that可省略.
I didn't expect (that) he could win the championship.
The teacher pointed out that Tom was not working hard enough.
② 引导主语从句.通常采用it作形式主语的句型.
That the earth goes around the sun is known to everyone.
（It is known to everyone that the earth goes around the sun.）
③引导表语从句.
The trouble is that we are short of money.
④引导同位语从句.
引导同位语从句的that和引导定语从句的that是不同的.前者只起语法作用,在从句中不作任何成分；而后者在定语从句中作主语、宾语或表语.举例说明：
The news that he resigned from office surprised us.
The idea that he holds is very common nowadays on campus.
2. that引导状语从句
①引导目的状语从句.
Bring it nearer that I may see it better.
②引导结果状语从句.
What have I done that he should be so angry with me?
③引导原因状语从句.
I am afraid that I will fail in the driving test.
④引导让步状语从句.意为“虽然、尽管”.
Difficult that/as the task was, they managed to accomplish it on time.
⑤引导条件状语从句.意为“假使、假设”.
Supposing that you were in my position, what would you do?
On condition that you were lost in the desert, you should ask for help as soon as possible.
3. 引导强调句.
It is Mrs. White that makes the decision in her family, not her meek little husband.
It is an ill wind that blows nobody good.
第四、that用作副词.
1. that用作普通副词.
I was that/so angry I could have hit him.
2. that用作关系副词.引导定语从句,可以代替when,where, why或 in which,常可省略.
I will never forget the evening (that) / when we went to the theatre.
The house (that)/where I used to live has been knocked down.
第五,与that 有关的常见重要短语.
1. in that,意为“既然、因为”.
Criticism and self-criticism is necessary in that it helps us correct our mistakes.
2. now that,意为“既然、由于”.
Now that they have taken matters into their hands, the pace of events has quickened.
3. see (to it) that,意为“注意、务必做到、保证”.
We will see to it that she gets home early.
See to it that you are not late again.
4. seeing that,意为“鉴于、由于”.
Seeing that it is 8 o'clock, we'll wait no longer.
Seeing that he was busy with his work, I didn't disturb him.
以上是that主要用法的概述,希望能对大家有所帮助.当然,that还有其他的一些用法,需要我们在学习的过程中不断地积累和总结.
参考资料：http://www.ecp.com.cn/edit/sample/dxsample/200512/705.htm