selecting a mobile phone is no easy task because technology is changing so rapidly.为什么用is changing而不用完成时态?

selecting a mobile phone is no easy task because technology is changing so rapidly.为什么用is changing而不用完成时态?
selecting a mobile phone is no easy task because technology is changing so rapidly.
为什么用is changing而不用完成时态?

selecting a mobile phone is no easy task because technology is changing so rapidly.为什么用is changing而不用完成时态?
他的意思是说技术是一直在改变着的,因此用进行式,完成时态则表示科技已经改变了,而实际情况是科技无时无刻都在改变.

科学技术是日新月异的，所以用进行时

is changing
现在进行，体现科技日新月异，时刻进步