You have 3 weights:1 kg,3 kg and 9 kg as well as an equal arm balance,as shown.How many different weight objects can you weigh with these three?[Remember the weights may be placed on either side] 翻译:你有3个砝码:1公斤、3公斤和9公斤,以及一个托盘天平,你可以称出多少个不同的重量?(记住砝码可以放在天边两边的任意一边)