one letter, several sounds: c in cat ("k") and city ("s")
silent letters: the k in know, the w in write
two letters, one sound: sh, ch, th
Many English letters have more than one sound, and one sound can be written in several ways. So when you learn a new word, learn how it sounds as well as how it's written. The dictionary shows the sound between slashes: /naɪt/ is how you say night.
Each vowel letter has a short sound and a long sound. The long sound is usually the name of the letter. An e at the end of a word is often silent and makes the vowel before it long.
C sounds like "k" before a, o and u, and usually like "s" before e, i and y. G sounds like "g" before a, o and u, and often like "j" before e, i and y – but not always: get and give have a "g".
Some pairs of letters make one sound.
Some letters are written but not said.
Saying every letter makes a word hard to understand.
Saying th as "s" or "t" makes a different word: think said as "sink" or "tink", three said as "tree".