句子的主语和动词必须在单复数表达形式上保持一致。单数形式的主语应当与单数形式的动词搭配。复数形式的主语应当与复数形式的动词联用。主语和动词的搭配非常重要，因为它可以防止读者搞不清哪个名词是主语。
- Example
- The girl is walking in the park.
这是一个简单的句子，读者能够清楚地分辨出句子的主语是“girl”。单数形式的动词“is”与单数形式的主语“girl”在数量表达上是一致的。
然而，对于更为复杂的句子，单复数匹配关系可能并不显而易见。例如，
- Incorrect
- Sample 1, in addition to Samples 2 and 3, were found to be contaminated.
- Correct
- Sample 1, in addition to Samples 2 and 3, was found to be contaminated.
在上例中，主语是“Sample 1”。但是，如果句中使用了复数形式的动词“were”，读者便很容易误认为主语不仅是“Sample 1”，而且还包括“Samples 2 and 3”。
Contents
主语和动词搭配的例子
| 动词 | 单数形式的主语 + 动词 | 复数形式的主语 + 动词 |
|---|---|---|
| Be | The study is novel. | The studies are novel. |
| Make | He makes a cake. | They make a cake. |
| Conclude | Goldmund concludes that 67% of the samples had been contaminated. | Goldmund and Millstein conclude that 67% of the samples had been contaminated. |
| Present | The figure presents the results of the simulation. | The figures present the results of the simulation. |
复合主语和动词
在一个句子中，一个动词可以有一个以上的主语。当两个或两个以上的主语共用同一个动词时，主语之间用连词“and”或“or”连接。由连词“and”连接的主语通常需要与复数形式的动词联用。
- Incorrect
- Composite A and composite C was discarded due to surface irregularities.
- Correct
- Composite A and composite C were discarded due to surface irregularities.
相比之下，由连词“(either…) or”连接的单数形式的主语须与单数形式的动词联用。
- Incorrect
- We concluded that either composite A or composite C have issues with surface irregularity.
- Correct
- We concluded that either composite A or composite C has issues with surface irregularity.
由连词“(neither…) nor”连接的单数形式的主语也须与单数形式的动词联用。
- Incorrect
- Neither sample B nor sample D were found to be contaminated.
- Correct
- Neither sample B nor sample D was found to be contaminated.
但是，如果用连词连接起来的主语是复数形式，则必须使用复数形式的动词。
- Incorrect
- Neither the patients in group A nor the patients in group B has histories of illness.
- Correct
- Neither the patients in group A nor the patients in group B have histories of illness.
有时，复合主语会同时包含单数形式和复数形式的名词。这时，动词的单数或复数形式应当与最接近它的主语名词的单复数形式相匹配。
- Incorrect
- Neither the main frame of the vehicle nor its additional components needs to be treated with the solution.
- Correct
- Neither the main frame of the vehicle nor its additional components need to be treated with the solution.
上例的正确用法是使用复数形式的动词“need”，因为“components”是复数形式。
主语用“and”连接的更多示例
用“and”连接的主语须与复数形式的动词联用。
- Example
- The puppy and the kitten are friends.
- Example
- The behaviors of lipids and proteins were studied in an isolated environment.
主语用“(either…) or”或“(neither…) nor”连接的更多示例
用“(either…) or”或“(neither…) nor”连接的单数形式的主语须与单数形式的动词联用。用“(either…) or”或“(neither…) nor”连接的复数形式的主语须与复数形式的动词联用。
- Example
- Either the vacuum chamber or the clean room has been damaged.
- Example
- Neither the vacuum chamber nor the clean room has been damaged.
- Example
- Either heor she waters the plants.
- Example
- It is rainy, so neither the park nor the beach is nice to walk on.
当主语既包含单数形式也包含复数形式的名词时，与这种复合主语相匹配的动词的单复数形式由最靠近动词的名词的单复数形式决定。在用“or”或“nor”连接的名词中，只要有一个名词是复数形式，动词就必须是复数形式，而且这个复数形式的主语名词应当放在紧挨着动词的地方。
- Example
- Either he or his daughters water the plants.
- Example
- Neither the clean room nor the vacuum chambers have been damaged.
当主语和动词分开时
许多句子带有短语或从句，导致主语和动词是分开的。这可能会造成主语难以识别。以下面两个句子为例，
- (a)
- Many studies on this subject has neglected the effect of oxygen on the fabrication process.
- (b)
- Many studies on this subject have neglected the effect of oxygen on the fabrication process.
哪个句子是正确的呢？答案是b。这是因为主语是“studies”，而非“subject”。使用正确的动词单复数形式，能够帮助读者更好地识别句子的主语。
- Incorrect
- We found that the derivatives of C demonstrates high heat resistance.
- Correct
- We found that the derivatives of C demonstrate high heat resistance.
通过正确使用动词的复数形式，上例中的第二个句子清楚地表明“derivatives”是主语。
其他连接词：along with，as well as，in addition to
像“along with”、“as well as”和“in addition to”这样的短语不是连词，但它们能够起到连接词的作用。如上所述，用连词“and”连接的多个主语通常须与动词的复数形式联用。但是，当使用“along with”、“as well as”和“in addition to”时，则不是这样。
- Incorrect
- Composite C, along with composite A, were discarded due to surface irregularities.
- Correct
- Composite C, along with composite A, was discarded due to surface irregularities.
- Incorrect
- Composite C as well as composite A were discarded due to surface irregularities.
- Correct
- Composite C as well as composite A was discarded due to surface irregularities.
- Incorrect
- Composite C, in addition to composite A, were discarded due to surface irregularities.
- Correct
- Composite C, in addition to composite A, was discarded due to surface irregularities.
这些连接词与“and”的区别在于，它们并不构成复合主语。在上述句子中，主语是“composite C”，而不是“composite C, along with composite A”、“composite C as well as composite A”或“composite C, in addition to composite A”。
不定代词
单复数形式的另一个常见的混淆之处是不定代词，比如“anything”是应该与单数还是复数形式的动词联用。有些不定代词总被当作单数，而另一些则总被当作复数。还有一些不定代词，根据句子的情况不同，有时被当作单数，有时则被当作复数。常见的不定代词包括： all, any, anything, anybody, anyone, anywhere, every, everything, everybody, everyone, everywhere, some, something, somebody, someone, somewhere, none, nothing, nobody, nowhere, more, most, another, each, one, both, either, few, many, several。
大多数不定代词被视为单数。“every”、“another”、“each”和“one”，以及所有以“thing”、“body”、“one”或“where”结尾的不定代词都须与单数形式的动词联用。
- Example
- Every sample was treated with the prepared solution.
- Example
- Another girl asks for paper.
- Example
- Each of the samples was treated with the prepared solution.
- Example
- Only one of the boys wants ice cream.
- Example
- Something is wrong.
另一方面，“both”、“few”、“many”和“several”则被视为复数。
- Example
- Both of the samples were contaminated with ammonia.
- Example
- Few are happy with the results.
- Example
- We found that many of the composites were damaged by exposure to air.
- Example
- Several children look for extra pencils.
根据句子的情况不同，有些不定代词可以被视为单数，也可以被视为复数。它们包括：all，some，any，none，more，most，either。请看下面使用不定代词“some”的例句。
- Example
- Some of the samples were contaminated.
Some of the sample was contaminated.
在上例的第一个句子中，“some”指的是“samples”，是复数形式，因此应当与复数形式的动词联用。在第二个句子中，“some”指的是“sample”，是单数形式，因此应当与单数形式的动词联用。
放在动词后面的主语
在有些句子中，主语跟在动词后面，而不是把动词跟在主语后面，例如，以“there”或“here”开头的句子，以及句子结构为倒装形式的句子。
- Example
- There are five equations that must be considered.
- Example
- Here is an equation that must be considered.
- Example
- Behind the building stands a trash can.
从上例可见，主谓语单复数形式一致的原则同样适用于主语置于动词后面的情形。
数字、百分比或数量作为主语
句子的主语有时可以是数字或数量。这在学术写作中尤为常见，因为数值对于科学研究来讲非常重要。与数字主语连用的动词单复数形式取决于数字所指的内容。
- Example
- 67% of the samples were found to be contaminated.
- Example
- 80 cm of electric tape was cut.
在上例中，“67%”指的是“samples”，是复数。因此，它需要与复数形式的动词“were”联用。而在另一句中，“80 cm”指的是“electrical tape”，是单数，因此应该与单数形式的动词“was”连用。同样的规则也适用于比例数字。
- Example
- Almost three-quarters of the samples were found to be contaminated.
- Example
- Almost three-quarters of the first sample was found to be contaminated.
如果主语指的是某个事物的一个整体数量，它应该被视为单数。
- Example
- 70 cm is not a sufficient length.
- Example
- 97.5% is a high accuracy that has not been previously achieved.
集体名词作为主语
集体名词是指一群人、动物或事物的名词。与这些名词搭配使用的动词单复数形式在美式英语和英式英语中具有不同的规定。在美式英语中，集体名词通常被视为单数；而在英式英语中，则被视为复数。
- Example
- (US) The flock flies to Russia in early summer.
- Example
- (UK) The flock fly to Russia in early summer.
鸟群指的是一群鸟。根据美式英语的习惯，“flock”应当与单数形式的动词联用。英式英语则规定，“flock”应当与复数形式的动词联用。这是因为美式英语强调鸟群的整体性，而英式英语则强调鸟群是由许多只鸟组成的。
在上例中，“强调”这个说法很关键，因为它可以决定句子的内容，并决定集体名词是作为单数还是复数处理。
- Example
- The flock squawk at each other.
- Example
- The flock is enormous.
在上例中，两个句子强调的重点有所不同。
不可数名词作为主语
不可数名词是抽象概念或一般术语，因此无法计数。不可数名词的例子包括：research, information, progress, equipment, furniture, luggage, flour, cementt。不可数名词通常与单数形式的动词联用。
- Example
- The research found the previous results to be invalid.
- Example
- Information is a strategic resource.
- Example
- The cement was poured over the foundation.
作为主语的首字母缩略词和缩写词
关于首字母缩略词和缩写词的规则比较简单，即检查这些词的非缩写原词是什么。首先，确定非缩写的原词是单数、复数、复合词或集体名词，然后使用相应的规则即可。
- Example
- This new SSD is perfect for my PC.
“SSD”代表“solid-state drive”，是单数，因此应当与单数形式的动词联用。
- Example
- BCS continue to experience the side effects of the treatments they were exposed to.
“BCS”代表“breast cancer survivors”，是复数形式，因此应该与复数形式的动词联用。