教程列表：

sea

score

science

save

sausage

sail

safe

sadly

sad

rush

run

round

round

roof

swum

swimmer

sweet

sweet

surprising

surprised

surprise

sure

sunny

summer

sugar

suddenly

such

study

strong

string

slow

asleep

sky

skin

skill

ski

size

single

singer

since

silly

sign

side

sick

shy

shut

show

shower

shout

should

shorts

shine

sharp

shape

several

set

serious

september

send

sell

seem

seed

seat

season

village

yet

yesterday.

wrong

written

writing

writer

worse

worried

world

work

work

word

wood

wonderful

wonder

without

wish

wing

windy

wind

win

wide

whole

while

while

whether

when

what

well

wet

well

weigh

weather

way

way

watermelon

warm

war

wake

waiter

wait

voice

visitor

visit

violin

vegetable

usual

upstairs

unusual