请教小白问题，多谢啦！

margaret

各位大侠们，

我刚接触会计，被那个税搞得晕乎晕乎的。有个问题没看懂。想请教大家一下，
教材里有个例子，说
Jim is a real estate agent contracted to sell Lorena's property. Lorena is a non-resident. The services are performed in Australia and therefore pass the test of being a taxable supply.
然后他的解释是As the service is directly connected to Australian real property, it cannot be GST-free.
我纠结的地方是在书的前一部分解释说：
Services performed in Australia can be GST-free supplies and not taxable supplies if
-The services do not relate to physical work in relation to goods or real property in Australia.
-The services are performed for a non-resident customer
-The resident customer is overseas when the services are performed and the effective use and enjoyment of the service also took place overseas.
如果我只看例子，我会觉得例子有道理，可我先看了条例，然后他举的例子让我觉得既然已经满足了第二条为啥还要有其他的要求。如果有其他的要求为啥条例里面不放进去。
麻烦大家知道的告诉我这个是为了啥。多谢多谢啦～！