$1.$Signed and typed names are both the non$-$essential components of the business letters$\mathrm{.}2.$If you are replying to an inquiry letter, you can begin with a line of thanks as the openingof the letter$\mathrm{.}3.$While wrting a letter, everything goes towards the right side margin$8.$A letter is one person's written message to another pertaining to some matter of common concern$\mathrm{.}9.$Writing the date and adding the signature is not important in the business letters$10.$You should always specify your needs and ask precise questions while writing the inquiry letters.