Spelling words with the silent letters 'h', 'p', 'n', 'l' and 's'

A silent 'h' can be found in different places within a word and next to different letters. A silent 'p' can be found in different places within a word and next to different letters. A silent 'n' is generally found at the end of the word after the letter m. A silent 'l' generally comes after a vowel and often changes the sound of the vowel. How to spell words with the silent letter 's' and the curriculum words: environment, twelfth and desperate.