The apple is in the tree or on the tree?

问题描述:

The apple is in the tree or on the tree?
I know should use "on the tree",but my English teacher told me to use "in the tree".I have consulted dictionaries,one said"the
pear on a tree",but another said "a bird on the tree".Can you give me some detailed example.(告诉在某本字典的多少页,要权威的字典,最好是高中课本!)Please use Chinese answer the question.Thank you very much!

是in the tree
苹果是长在树“里面的”,没摘下来之前是属于树的一部分
鸟是站在树上面,不属于树的一部分,是on the tree
除非鸟躲在树里面,被遮住你看不见,可以用in the tree