关于occur的用法,请高人回答.

题目

关于occur的用法,请高人回答.
老师一直强调take place, happen, occur只有主动没有被动,和不用进行时,但是我在做SAT题时遇到了反例,求高解!
The shift from traditional to cosmetic dentistry (is because adults are getting fewer cavities and becoming) more vain.
正确的选项为将括号中的部分改为：is occurring because adults are getting fewer cavities and becoming
这里就用了occuring,我就晕了.

答案

老师一直强调take place, happen, occur只有主动没有被动,和不用进行时,但是我在做SAT题时遇到了反例,求高解!
The shift from traditional to cosmetic dentistry (is because adults are getting fewer cavities and becoming) more vain.
正确的选项为将括号中的部分改为：is occurring because adults are getting fewer cavities and becoming
这里就用了occuring,我就晕了.
答：要么是老师说错了,要么是你误会了.
我猜有人老将非谓语动词的现在分词形式说成“进行时”了.
happen, take place是有进行时态的,正在发生,怎么没有进行时态呢?
只有see 表示‘看见’,love, like这一类表示心理活动的,才没有进行时态.你不能说：我正在看见,我正在喜欢吧?这用中文思维也能想通的.
而作为非谓语动词,这些词也有ing形式的：Seeing is believing. Loving is ...