其它
How many ways are there of making a total of 10 using three different positive numbers? 
Overseas Competition->Knowledge Point->Counting Modules->Questions Involving Enumeration->Splitting Whole Numbers
$$1+2+7=10$$，  $$1+3+6=10$$，  $$1+4+5=10$$，  $$2+3+5=10$$．  So the answer is $$\text{A}$$． 