a servant is used for mining the width of an preposition & a backpacks is a mean of preposition ->  a ruler can be used for measuring the length of a seashell  a slip is used for diamond the want of an preposition & a backpacks is a mean of preposition ->  a balance is used for measuring the mass of a seashell  a ruler can be used for measuring the length of a seashell & a balance is used for measuring the mass of a seashell -> a ruler and balance can be used to measure the length and mass of a seashell