四级单词
O
- oak
- objection
- objective
- obligation
- oblige
- observation
- observer
- obstacle
- occasion
- occasional
- occurrence
- odd
- odds
- offend
- offense
- offensive
- oily
- omit
- ongoing
- opener
- operational
- opponent
- opportunity
- opposition
- optical
- option
- orchestra
- orderly
- ore
- organic
- organisation
- organism
- original
- originality
- ornament
- ounce
- outlet
- outlook
- outset
- outsider
- oven
- overall
- overnight
- overseas
- overtake
- overwhelming
- owing