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The other day I read this sentence in a student’s piece of work:
The number of cars was risen 10% over the last five years….
You are right if you think this looks wrong – it is wrong! But it is not unusual to see sentences like this. The general structure of the sentence is sound (word order, use of articles etc) but the student doesn’t know how to build up compound verbs properly. (The correct version is: The number of cars has risen / has been rising over the last five years..) I know that things get pretty difficult with auxiliary verbs and when a sentence is in the passive voice – a new bridge has been built in the city centre – there are even more things to get wrong with building up compound verbs. However, guys, don’t just guess! There are only a few possibilities that you can use. Take a look again at the sentence:
The number of cars was risen 10% over the last five years….
Once you have decided that the subject of the sentence is singular (the number) and the verb is active then the grammatical possibilities for the verb are:
1. The number of cars rises over the last five years….
2. The number of cars is rising over the last five years….
3. The number of cars has risen over the last five years….
4. The number of cars has been rising over the last five years….
5. The number of cars rose over the last five years….
6. The number of cars was rising over the last five years….
7. The number of cars had risen over the last five years….
8. The number of cars had been rising over the last five years….
Any of these sentences, even the wrong ones, read far better than the original sentence that I gave you. It is also suprising that actually a fair number of them are acceptable and would not upset the reader too much! If you are not sure of the possible verb forms take a look at a verb chart like the one here on Englishpage.com. When you follow the link scroll down the page to the VERB TENSE OVERVIEW table towards the bottom of the page. You can see all the tenses laid out. Use what you think is the most appropriate one and make sure you make your verb agree with the subject of the sentence. Even if you choose the wrong tense your writing will be far more acceptable than if you put something grammatically impossible!