countable and uncountable nouns

Mary must eat ... meat be­cause she has problems with her blood pressure

There are ... new pic­tures in this room. 

Thanks awfully for the books you sent me yesterday. — Don't mention it, it wasn't ... bother. 

. ... of their an­swers were excellent. 

. My mother says I eat ... 

There were ... plates on the table. 

... of her advice was useful

There are ... teachers at our school.

Please don't put ... pepper on the meat

She wrote us ... let­ters from the country.