Silent B

B is not pronounced when following M at the end of a word.

climb

crumb

dumb

comb

Silent C

C is not pronounced in the ending "scle"

muscle

Silent D

D is not pronounced in the following common words:

handkerchief

sandwich

Wednesday

Silent E

E is not pronounced at the end of words and usually makes the vowel long.

hope

drive

gave

write

site

Silent G

G is not often not pronounced when followed by an N

champagne

foreign

sign

feign

Silent GH

GH is not pronounced before T and at the end of many words

thought

through

daughter

light

might

right

fight

weigh

Silent H

H is not pronounced when following W. Some speakers whisper the H before the W.

what

when

where

whether

why

Silent H

H is not pronounced at the beginning of many words. Use the article "an" with unvoiced H. Here are some of the most common:

hour
honest
honor
heir
herb

Pronounced H

H is pronounced at the beginning of these common words. Use the article "a" with voiced H.

hill

history

height

happy

hangover

Silent K

K is not pronounced when followed by N at the beginning of a word.

knife

knee

know

knock

knowledge

Silent L

L is often not pronounced before L, D, F, M, K.

calm

half

salmon

talk

balk

would

should

Silent N

N is not pronounced following M at the end of a word.

autumn

hymn

Silent P

P is not pronounced at the beginning of many words using the suffix "psych" and "pneu".

psychiatrist

pneumonia

psychotherapy

psychotic

Silent S

S is not pronounced before L in the following words:

island

isle

Silent T

T is not pronounced in these common words:

castle

Christmas

fasten

listen

often

whistle

thistle

Silent U

U is not pronounced before after G and before a vowel.

guess

guidance

guitar

guest

Silent W

W is not pronounced at the beginning of a word followed by an R.

wrap

write

wrong

Silent W

W is not pronounced with these three pronouns:

who

whose

whom

 

Source: esl.about.com