1. You can’t end a sentence with a preposition 不能以介词结尾

一般情况因该避免以介词结尾。但以下四种情况用介词结尾却更自然。

被动结构：passive structures

 (she enjoys being fussed over.她喜欢被簇拥的感觉)

条件从句：relative clauses

 (they must be convinced of the commitment that they are taking>不定式结构infinitive structures

 (Tom had no-one to play with.没有人可以和汤姆一起玩)

Who、where、what打头的问句：questions beginning with who, where, what, etc.

(what music are you interested in?你喜欢什么样的音乐？)

2. You can’t start a sentence with a conjunction 不能以连词开头

Conjunctions are words such as and, but, so, and if, which are used to connect clauses, sentences, or words. This grammatical superstition arises from the thought that because these words are used to connect separate clauses.The argument against using and or but to introduce a sentence is that such a sentence expresses an incomplete thought (or ‘fragment’) and is therefore incorrect. However, this is a stylistic preference rather than a grammatical rule.

连词包括and、but、so、if等词语，用于连接从句、句子或单词。人们认为这些词是用来连接独立的从句，所以才有了这种错误观点。还有人认为使用and或者but来引出的句子表达的观点使不完真给的，所以是不正确的。不过，这只是一个风格的偏好，而不是语法规则。

3. Double negatives are always ungrammatical 双重否定不符合语法规则

When two negatives are used to communicate a negative, then the usage is ungrammatical. The reason for this is that two negatives actually cancel each other out and create an affirmative statement. For example, the sentence ‘I don’t have nothing for you’is ungrammatical because the presence of two negatives technically switches the meaning to an affirmative>

当两个否定词汇一同使用时，这种用法是不符合语法规则的。原因是两个否定实际上互相抵消，表达肯定的含义。例如，这句话“I don’t have nothing for you”不符合语法，因为严格意义上来讲这两个否定词汇在一起表达了肯定的含义，表示“我有东西给你”。

Even though the use of double negatives in formal speech and writing is nonstandard, the use of double negatives is common in areas such as informal speech and popular music.

即使在正式演讲和写作中使用双重否定是不标准的，但在非正式的演讲和流行音乐等领域双重否定是很常用的。

However, there is one use of double negatives that is entirely grammatical. In this use, the double negative is used to express and reinforce an affirmative

然而，有一个双重否定的使用是完全符合语法的。在使用双重否定表达肯定或者加强肯定语气的。

I couldn’t not help him. [meaning: I strongly felt I should help him]

我要帮助他。

4. Splitting infinitives is a mistake 不定式不能分隔使用

For the uninitiated, splitting infinitives is the practice of placing an adverb between ‘to’and the corresponding verb, as in ‘to lightly tap.’Splitting infinitives is a common peeve of grammar enthusiasts, but like many such peeves it has been employed by well-regarded English prose stylists for centuries. However, take care before splitting those infinitives; many style guides and professors would still consider this a stylistic error.

对外行人来说，分裂不定式是在to和之后的动词之间放置一个副词，如“to lightly tap（轻拍）”。分裂不定式对语法爱好者而言是个常见的让人苦恼的问题。但是有很多著名的英文散文家喜欢使用分裂不定式的写作方式。不过，要小心使用分裂不定式，仍然有文体书和专家认为这是文体错误。

例如：

She used to secretly admire him.
她曾经偷偷爱慕他。

You have to really watch him.
你必须真得看着他。

Those who believe that split infinitives are grammatically incorrect would rewrite these sentences as:

认为分裂不定式不符合语法规范的人会主张这样改写上面的句子：

She used secretly to admire him.
她曾经偷偷爱慕他。

You really have to watch him.
你必须真得看着他。

5. You can’t start a sentence with hopefully  hopefully不能作为句子开头

This use of hopefully to mean ‘it is hoped’rather than the adverbial ‘in a hopeful manner’has been disputed in the past several years, though it has found its way into general acceptance.

hopefully这个词的意思是“有希望地”，而不是状语“以一种充满希望的方式”。在过去的几年里，这种用法虽然已经被普遍接受但一直有争议的。

Hopefully and thankfully can’t be reworded along the lines of other sentence adverbs, using the constructions ‘it is hopeful that’or ‘it is thankful that’:

Hopefully 和thankfully和其他句子副词不同，可以使用‘it is hopeful that’ 或者‘it is thankful that’的结构

Hopefully, planning delays will be minimal.

希望比赛尽可能不被推迟。

It is hopeful that planning delays will be minimal.

希望比赛尽可能不被推迟。

也可以这样改写：

It is to be hoped that planning delays will be minimal.

希望比赛尽可能不被推迟。

（来源：沪江英语）