There are 3 grams, 2 grams, and 4 grams each. Choose one or more of them. How many objects with different masses can be directly weighed on the balance.
有3克、2克、4克的砝码各一个，选其中一个或几个，能在天平上直接称出多少种不同质量的物体．
<gadget id="calculator">3 + 3 + 1</gadget>
<output>7</output>

<result>7</result>