5035.oak(名)橡樹、橡木
This table is made of solid oak.
這張案子是用實心橡木制作的。

5036.oath(名)宣誓、誓約；詛咒
Government employees swear an oath not to reveal official secrets．
政府雇員宣誓不泄露官方機密。

5037.obligation(名)義務；人情債
You are under no obligation to buy anything.
你不必非買什么東西不可。

5038. oblige(動)使感激：迫使
People who cannot find time for recreation are obtiged sooner or later to find time for illness.
擠不出時間休息娛樂的人遲早會被迫擠出時間養病。

5039.observant(形)善于觀察的
Observant walkers may see red deer along this stretch or the road.
觀察敏銳的步行者能在這一路段看到赤鹿。

5040.observation(名)觀察；評論
Observations were made of the children at the beginning and at the end of pre-school and first grade．
這個觀察是針對孩子們在學齡前和小學一年級開始和結束時的情況所做的。

5041.observatory(名)天文臺、氣象臺
The stadium lights polluted the sky around the observatory.
體育館的燈光使得天文臺周圍的夭空不那么適宣觀測了。

5042.observe(動)觀察；遵守
Every driver should observe the speed limit.
每個司機都應當遵守速度限制規定。

5043.observer(名)觀察者、目擊者
He was sent along as an observer.
他被派作觀察員。

5044.obstacle(名)阻礙
when a big stone blocks the way,the brave view it as a stepping stone;the weak as an
obstacle.
大石攔路，勇者將它視為前進的階梯，弱者將它視為前進的障礙。

5045.obstruct(動)阻隔、遮斷
The crash obstructed tha road for several hours.
撞車事故把道路阻塞了幾個小時。

5046.obtain(動)獲得
He failed to obtain a scholarship.
他沒有獲得獎學金。

5047.obstinate(形)固執的
同義詞stulbbom
He can be very obstinate when he wants to be!
他的強勁一上來，簡直拗得要命！

5048.obvious(形)明顯的
His nervousness was obvious right from the start．
他從一開始就顯得十分緊張。

5049.obviously(副)明顯地
Obviously，we don't want to spend too much monney.
很明顯，我們不想花太多的錢。

5050.occasion(名)場合；機會；理由
I can remember very few occasions when he had to cancel because of ill health.
我記得他因為健康不佳而被迫取消的情況絕無僅有。

5051.occasional(形)偶然的
She likes an occasional glass of wine.
她偶爾喝杯酒。

5052.occasionally(副)偶爾
They occasionally go to a theater in these days.
這些日子他們偶爾去劇院。

5053.occur(動)發生；存在
后接介詞to
Something unexpected occurred.
發生了一件出乎意料的事。

5054.occurrence(名)事件
Satellites have extended the power of communications to report events at the instant of occurrence.
衛星使通訊具有了報導即時發生事件的能力。

5055.odd(形)古怪的；奇數的；奇持的
同義詞pecliar
I find it odd that she hasn't written to us.
我覺得她沒寫信給我們有點奇怪。

5056.odds(名)勝算；可能的機會
慣用復數
The odds are heavily against him.
他成功的幾率很小。

5057.offer(動)(名)提議，提供
(動):Josie had offered her services as a guide.
喬西曾表示愿意當向導。
(名):You can't just turn down offers of work like that.
人家給你工作，你不能就那樣一一謝絕呀。

5058.offspring(名)子孫、后代、后裔
The stomic bomb is the offspring of the 20th century physics.
原子彈是20世紀物理的產物。

5059.onset(名)進攻、襲擊
The fierce onset of the enemy broke the ranks of the army．
敵人的猛烈攻擊致使全軍大亂。

5060.opera(名)歌劇
Does opera interest you?
你對戲劇感興趣嗎？

5061.operate(動)操作、見效
Solar panels can only operate in sunlight.
太陽能電池板只能在日光下起作用。

5062.operation(名)手術；經營；運算
Will need to have an operation?
我需要動手術嗎？

5063.operational(形)操作上的、管理的
The new airport should be fully operational by the end of the year.
新機場應在年底前全面投入運營。

5064.operator(名)接線生
Dial 100 and ask for the operator.
請撥100找接線員。

5065.opinion(名)意見、評價
We were invited to giVe our opinions about how the work should be done．
我們應邀對于如何開展工作提出意見。

5066.oponnent (名)對手
Someone has said that thare's no etarnal friend or opponent in the business cicles.
有人曾說過，在商場上，沒有永遠的朋友,也沒有永遠的敵人。

5067.oppose(動)反時
This party would bitterly appose the reintroduction of the death penalty.
該黨會強烈反對恢復死刑。