Many other changes in vowels have taken place over the centuries (see the separate articles on the low back, high back and high front vowels, short A, and diphthongs). These various changes mean that many words that formerly rhymed (and may be expected to rhyme based on their spelling) no longer do. For example, in Shakespeare's time, following the Great Vowel Shift, "food", "good" and "blood" all had the vowel , but in modern pronunciation "good" has been shortened to , while "blood" has been shortened and lowered to in most accents. In other cases, words that were formerly distinct have come to be pronounced the same – examples of such mergers include "meet–meat", "pane–pain" and "toe–tow".