who, that , what, preposition + which
1) Thank you for your e-mail in which you enquired about our products.
2) Your statement of account that we received last week, appears to have a number of errors that refer to items we did not order.
3) I would like to speak to Mr.Baker, who phoned me this week, concerning our account, that he says has not been cleared.
4) Would you please clear your balance that has been outstanding since last January.
5) To my mind, you need to contact the person who deals with foreign transactions.
6) An agent who sells products on his own account can set his own prices and profit margins.
7) Thank you for your letter of 12 April 2006 in which you asked us to give your company a ten per cent discount on your order.
8) Insurance underwriters offer two types of policy that would be suitable for your requirements.
9) With regard to the changes of our terms of payment that you asked for we suggest you should use Banker's Drafts.
10) We would like to remind you still owe our bank 2000$ that we want you to pay before the end of April