Android Studio：可绘制文件夹：如何为多个dpi放置图像？

Hi as per android documentation the drawable folder needs to have multiple sub-directories for images of different dpis. However in Android Studio creating any sub directory in the drawable folder causes it to fail to detect any images at all. On the other hand if an image is placed directly in the drawable folder it gets detected and becomes available for use view R.drawable.ImageName. In this case how do we use different dpi images for the same ImageName? the drawable fo