There is no single letter for the sounds we hear in 'shoe' ([FONT="]/ʃ/[/FONT][FONT="][/FONT][FONT="][/FONT]) or 'chew' ([FONT="]/ʧ/[/FONT]). Although the former is often represented by the letters sh, and the latter by the letters ch, there are other ways, for example :
[FONT="]/ʃ/[/FONT][FONT="][/FONT][FONT="]: shoe, machine, passion, delicious, caution, sugar, cons[/FONT][FONT="]c[/FONT][FONT="]ience, schedule (some speakers) [/FONT]
[FONT="]/ʧ/[/FONT][FONT="]: chew, [/FONT][FONT="]cello, [/FONT][FONT="]hatch, nature, Tuesday (some speakers) [/FONT]