Confused sentences

I need some advice on the correct use of words as indicated below :-

1. Keep up the good work.Read more books and newspaper to improve your vocabularies .

My suggestion : The word " vocabularies " should be in the singular form.
Am I right ? Please advise .

2. According to a policeman who was handling the case , the accident happened about 12.30am.

Am I right if I were to change "a policeman" to " the policeman " because the sentence referred to a specific policeman .

[Tdol]

1- vocabulary should be singular. To make a plural, we use 'vocabulary items'.
2It depends on whether there was one policeman in charge or more than one. It could be 'a' or 'the' depending.

[RonBee]

1. As tdol noted, vocabularies is not used.

2. It would certainly be appropriate to use the policeman if there was only one policeman handling the case. Otherwise, a policeman is definitely the way to go.

:)