Communication through exchange of letters is known as correspondence. We
communicate our feelings, thoughts, etc. to our friends and relatives through letters
that are called personal correspondence. A businessman also writes and receives
letters in his day-to-day transactions.
They are called business correspondence. Business correspondence or business
letter is a written communication between two parties. Businessmen may write
letters to suppliers of goods and also receive letters from the suppliers. Customers
may write letters to businessmen seeking information about availability of goods,
price, quality, sample, etc. or place an order for purchase of goods. Let us learn the
details about some important business letters.
The Enquiry (Inquiry) Letter. You send an inquiry when you wish to have some
information on a product or its sale (after you have seen the product advertised, or
displayed at a fair or exhibition, or you have only heard about it).
The Quotation Letter (a reply to the enquiry)– is a short letter enclosing the
required catalogues and price-lists, a brochure, etc. Some 'sales talk', such as 'We
are sure our high-quality products will meet your requirements, and we are looking
forward to your early order' is generally included.
The Letter of Complaint is sent by the customer when after receiving the goods he
finds that they are not up to order. They may be of the wrong size or colour, their
quality might be inferior, there might be a shortage of quantity or weight, etc.
When you have a complaint, you relay this information in a professional and
ethical manner to the person you have the problem with.
The Letter of Apology is a reply to the letter of complaint. The Letter of Apology
should be courteous, even if the complainant has abused you. You should be
truthful – if you have already been having trouble with the product, say so. Try to
sound sincere, and, where necessary, be prepared to take full responsibility

If I were  you, I wouldn't have said what you said yesterday.

If Jane had known that Tim didn’t have much money at him, she wouldn't have allowed him to pick up the tab.

You are so lazy, my friend! If you do not work hard, you will fail at the exams in June.

“If she had been waiting for somebody, she wouldn't have been wearing the bathrobe”, said the policeman about the murdered woman.

Calm down! If you were not so excited, it would be easier for us to help you.

Look, if you had stopped eating cakes and sweets when the doctor told you, you would have less problems with your weight and health now.

Ben would have enjoyed the main course if he had not eaten all the appetizers before it was served.

If you were not tired, we could go to the wine bar, but you look exhausted so we are going home.

If there were a fixed price menu, we would have to eat what they offer.  

Many years ago, in his childhood if Ken had seen a platter of sweets, he would not have stopped eating till there was nothing left.

With the first day of spring, when the awakening earth puts on its garment of green, and the warm, fragrant air fans our faces and fills our lungs and appears even to penetrate to our hearts, we experience a vague, undefined longing for freedom, for happiness, a desire to run, to wander aimlessly, to breathe in the spring. The previous winter having been unusually severe, this spring feeling was like a form of intoxication in May, as if there were an overabundant supply of sap.

One morning on waking I saw from my window the blue sky glowing in the sun above the neighbouring houses. The canaries hanging in the windows were singing loudly, and so were the servants on every floor; a cheerful noise rose up from the streets, and I went out, my spirits as bright as the day, to go—I did not exactly know where. Everybody I met seemed to be smiling; an air of happiness appeared to pervade everything in the warm light of returning spring. One might almost have said that a breeze of love was blowing through the city, and the sight of the young women whom I saw in the streets in their morning toilets, in the depths of whose eyes there lurked a hidden tenderness, and who walked with languid grace, filled my heart with agitation.