第五讲
名词性从句
[全析考法]
单句语法填空/单句改错
1．(2018·11月浙江高考)It is possible ________ caffeine may cause birth defects (缺陷) in humans, too.
解析：that 分析句子结构可知，该句是一个主从复合句，it作形式主语，that从句为真正的主语。
2．(2017·天津高考改编)She asked me________ I had returned the books to the library, and I admitted that I hadn't.
解析：whether/if 句意：她问我是否已经把书还给图书馆了，我承认说我还没有还。分析句子结构可知，空格处引导宾语从句，且在从句中不作任何成分，只起连接作用；又根据句意可知此处表示“是否”，故用whether或if引导宾语从句。
3．(2016·北京高考改编)The most pleasant thing of the rainy season is________ one can be entirely free from dust.
解析：that 句意：雨季最令人高兴的事情就是人们可以完全远离灰尘。分析句子结构可知，本句包含一个表语从句，且表语从句中句子结构完整，故使用that引导表语从句，that在表语从句中不作句子成分，只起连接作用。
4．(2016·天津高考改编)The manager put forward a suggestion ________ we should have an assistant. There is too much work to do.
解析：that 句意：经理提出了一个建议，我们应该有一个助手。工作太多了。分析句子结构可知，空处引导同位语从句，解释说明suggestion的具体内容，故填that。
5．(2016·江苏高考改编)It is often the case________ anything is possible for those who hang on to hope.
解析：that 句意：通常情况下，对于那些坚持希望的人来说，一切皆有可能。空处引导主语从句，从句中不缺少任何成分且意思完整，故使用that引导。
6．(2015·全国卷Ⅱ)After looking at the toy for some time, he turned around and found where his parents were missing.________________
解析：where→that或去掉where found后是一个宾语从句，不缺少句子成分且句意完整，所以不能用where，应该用that引导，that也可省略。
从属连词that, whether与if引导的名词性从句
[谨记规则]
(一)that引导的名词性从句
that引导名词性从句时本身无意义，只起连接作用，也不在句中作任何成分。它引导的名词性从句结构和意义都完整，往往用于陈述事实。引导主语从句、表语从句和同位语从句时，that不能省略。引导宾语从句时，在口语和非正式文体中，that可省略。但下列情况下，that不可省略：
1．that从句作介词的宾语；
I don't know exactly where he lives, except that it's somewhere out in the wilds.他具体住在哪里我不是很清楚，只知道是远离城市的边远地区。
2．that引导的从句位于句首时；
That the earth goes around the sun is known to us all. 众所周知，地球围着太阳转。 3．宾语从句前有插入语时；
We hope, on the contrary, that he will stay at home with us.恰恰相反，我们希望他和我们待在家里。
4．动词后有多个that引导的宾语从句时，只有第一个that可省略，从第二个从句开始that不可省略；
He told me (that) he had to leave and that he would be back soon.他告诉我他得离开并且很快就会回来。
5．it作形式宾语时，that引导的宾语从句中that往往不可省略。
He has made it clear that the meeting will not be postponed.他清楚地表明会议不会被推迟。
(二)that引导主语从句时可用it作形式主语的四大句式
1．It＋be＋形容词(necessary, right, likely, unlikely, wrong, important, certain, clear, obvious, strange, normal等)＋that从句
It isn't likely that I should accept such an offer as that. 我不可能接受像那样的帮助。
2．It＋be＋名词(短语)(a pity, a shame, good news, a fact, an honour, a wonder, no wonder等)＋that从句
It's no wonder that he didn't want to go.难怪他不想去。
3．It＋be＋过去分词(said, told, heard, reported, decided, suggested, advised, ordered, remembered, thought, considered, well-known, announced等)＋that从句
It is decided that the meeting has been put off until next Monday.会议被推迟到下周一已经定下来了。
[特别注意] 在“It＋be＋suggested/advised/ordered/requested/insisted/required ...＋that从句”结构中，从句谓语应用“(should＋)动词原形”。
It is suggested that you (should) spend more time in studying English.建议你花更多的时间学习英语。
4．It＋特殊动词或短语(seem, appear, happen, matter, turn out, occur to, make no difference等)＋that从句
It suddenly occurred to her that Joe was afraid of being alone. 她突然想到乔害怕独自一个人待着。
(三)whether与if的用法 1．用whether或if均可的情况
(1)whether可引导各种名词性从句。引导大部分动词后的宾语从句时，两者均可。 (2)it作形式主语，且主语从句在句末时，两者均可引导主语从句。 It's uncertain whether/if he'll come this evening. 他今天晚上是否会来还不确定。 2．用whether而不用if的情况 (1)主语从句和宾语从句置于句首时；
Whether we can have clean drinking water lies in what effective measures will be taken by the government about water pollution.我们能否有干净的饮用水取决于政府将采取什么样的有效措施处理水污染问题。
(2)引导表语从句和同位语从句时；
The problem is whether the air pollution can be controlled.问题是空气污染能否被控制住。 He asked me the question whether we should give money to the homeless. 他问了我我们是否该给无家可归者钱的问题。 (3)引导介词的宾语从句时；
It depends on whether we have enough time. 这取决于我们是否有充足的时间。 (4)引导词与or not连用时；
I don't know whether or not the report is true. ＝I don't know whether the report is true or not. 我不知道这个报道是否是真的。 (5)引导词后接to do时；
They don't know whether to go there. 他们不知道是否去那里。
(6)有些动词如leave, put, discuss, decide等后的宾语从句； We discussed whether we should hold a meeting. 我们讨论了我们是否应召开一个会议。 (7)避免用if引导产生歧义。
2020高考英语新创新大一轮复习人教全国版讲义语法突破专题化第三部分第五讲名词性从句含答案
