O字母开头的单词或词组(第8页)：
- once upon a time
- ozone layer
- on earth
- on business
- orally
- once in a while
- outdoor activity
- ouch
- on a farm
- over and over again
- outweigh
- Odysseus
- Oswald
- on the other band
- obesity
- opposed
- on the whole
- outer
- on behalf of
- occur to
- object to
- occasionally
- out of order
- once more
- outward
- Oceania
- out of respect
- owe to
- odour
- odourless
- offending
- out of breath
- overhear
- overboard
- observation
- organic
- olive
- one after another
- operator
- or so
- Obon
- ought to
- on purpose
- out of work