The function of any language is to communicate meaning, and grammar helps to serve that function. Meaning can be entirely clear and grammar can still be faulty, just as the meaning can be entirely clear in a sentence with many typos, i.e. misspelt words. Even when a listener or a reader might have no problem to understand the meaning conveyed by supplying the omitted word, the omission might still be an error if the word is essential to the grammar of the sentence.
Omission of Parts of “Adverbial Phrases”
For example, in the sentence – “The stock has always performed as well or better than expected.” essential words, i.e. the adverbial phrase ‘as well as or better than expected’ should be used. This type of grammatical errors are common in sentences that include such adverbial phrases as: ‘as well as … or better than‘, ‘as much as… if not more than expected’ (than expected cannot be omitted here). “The company share price has dropped as much if not more than” is a similar error.
The correct sentence structure is – ‘This year the company share price has plunged as much as last year, if not more.’
Some more examples: ‘The stock has always performed as well as it was expected to perform or better (‘than it was expected’ – can be omitted). This year the share price has gone up as much as by 5 % if not more. The stock has always performed as well as it was expected to perform or better. (than it was expected – can be omitted).
‘Like the thieves, the cops’ view of law enforcement is complex.’ – Here we are making a false comparison between ‘the thieves’ and ‘the cops’. The correct sentence is ‘Like the thieves’, the cops’ view of law enforcement is complex.’ or: ‘The cops, like the thieves, have a complex view of law enforcement.’
Another similar type of error is in the sentence – ‘Profits were not so high as the preceding year.’ or ‘Profits were higher than the preceding year.’ – here we are making a false comparison between ‘profits’ and ‘the preceding year’. The correct sentence structure is ‘Profits were not as high as they were in the preceding year.’ Here we can leave out “they were”, i.e.’Profits were not as high as in the preceding year.’, or we can leave out “in” (in the phrase – in the preceding year) but leave “as they were”, i.e. ‘The profits were not as high as they were preceding year.’ Another example is “The performance-based bonuses will be provided to the employees on Friday.” (“on” can be omitted in spoken language). Such errors are very often overlooked because the meaning is still understood by the listener.
Omission of Verb Forms
You might be surprised but “He either will or has already left” is grammatically incorrect. Even native speakers make such mistakes. The verb form “left” – (i.e. the participle two or past participle) is appropriate with the auxiliary verb “has”, but inappropriate with “will”. The correct sentence is “He either will leave or has already left.” Similarly, the sentence – ‘The country has already and will continue going to the dogs.’ is wrong. As you might have guessed the verb “gone” should be supplied after “already”, i.e. “has already gone”. The correct structure is “The country has already gone and will continue going to the dogs.”
Here the grammar rule is the following: if the form of the repeated verb changes, it cannot be omitted in the first part of the sentence and supplied only in the second part of the sentence. The verb can be omitted in the first part of the sentence if it does not change the form, e.g. “He either is now or will soon be leaving.” “leaving” is the same form which should be used both with “is” and “will”. Please note, that the omission may not always please the ear.
Changed verb forms can often be omitted in the second part of the sentence, e.g. ‘I used the car, when my father wasn’t.” ‘He didn’t go but should have.’ ‘He hasn’t gone but will.’ Here the grammar rule is the following: when the verb is omitted in the first part of the sentence, it is an error, but when it is omitted in the second part of the sentence, it is permissible, though may be undesirable.
When there is no auxiliary verb but a verb changes form because of a change in person, the verb can be omitted in the second part of the sentence, e.g. “I need the car because I drive more than she.”(i.e. she drives) or “I supply him financially, his mother emotionally” (i.e. his mother supplies).
Sometimes an omitted verb has the same form as a supplied verb but a different meaning, e.g. “He is crazy already and quickly driving his wife crazy.” This sentence may look fine, but the omission of “is” in the second part is at best questionable. The same verb should not be forced to carry two different meanings, ‘is’ is the auxiliary verb that is most often wrongly omitted. And the last example – “You better do it right now.” – is a very common mistake. Surprised? Like any other error it can legitimately appear both in spoken and written English. The auxiliary verb “had” is omitted in the phrase you had better. It can be contracted in writing – ‘You’d better do it right now.’ which is blurred to “You better” in spoken language and used with a commanding tone, nonetheless the correct imperative form is ‘You do it right now.’