1.普通动词：格式+ing; think---thinking
sleep---sleeping
study---studying
speak---speaking
say---saying
cry---crying
2.以不发音的e结尾的动词：去掉e再加ing，格式：去e+ing
wake---waking make---making
come---coming
take---taking
leave---leaving
have---having
dance----dancing
ride----riding
write---writing
3. 以重读闭音节结尾，呈现“辅，元，辅”结构的动词，先双写末尾的辅音字母，再加ing
stop---stopping
sit---sitting
run---running
forget---forgetting
begin---beginning
cut---cutting
get---getting
hit---hitting
set---setting
swim----swimming
fit---fitting
dig---digging
shop---shopping
put---putting
travel---travelling(可双写也可不双写)
refer---referring
prefer---preferring
4. 以 ie 结尾的动词，把 ie 改为 y ，再加 ing
lie---lying
die---dying
tie---tying
