b: i think it is an oak tree. it is certainly large enough to be one.
oak
n. １．栎树，橡树；２．栎木，橡木
a: oh no, i’ve dropped an oar .
b: we will have to swim to the shore now.
oar
n. 桨，橹
a: please tell me the big secret.
b: sorry, i took an oath and swore that i wouldn‘t.
oath
n. １．誓言，誓约；咒骂，诅咒语
on / under oath 在法庭上宣过誓
a: my pupils are so obedient , they always do their home work.
b: you are lucky, mine are terrible.
obedient
a. 服从的，顺从的
a: robert told an obscene joke last night.
b: is it too rude to repeat to me?
obscene
a. １．淫秽的，下流的；２．可憎的，可恶的
a: did you understand the theatre performance?
b: no, it was too obscure for me.
obscure
a. １．不着名的，不重要的；２．费解的，模糊不清的；３．隐藏的，偏僻的
vt. 使变模糊，掩盖
a: you are always playing video games.
b: i know. i have an obsession.
obsession
n. 困扰，无法摆脱的思想（或情感）
a: excuse me, but your car is obstructing the entrance to my home.
b: oh, i’ll move it right away.
obstruct
vt. １．阻塞，堵塞；２．阻碍，阻止，妨碍
a: can i move into the apartment today?
b: no, you can have occupancy next week.
occupancy
n. 占有，使用，居住
a: what is that terrible odour ?
b: oh, sorry, it must be my socks.
odour
n. 气味
a: beverley looked stunning at the party.
b: yes, her outfit was offset by her jewelry.
offset
vt. 补偿，抵消
a: do you have any offspring ?
b: yes, i have three daughters.
offspring
n. １．子女，子孙，后代；２．（动物的）崽
a: do you like olives ?
b: yes, especially black ones in salad.
olive
n. 橄榄，橄榄树
a: is that glass clear?
b: no, it is opaque , that is why you are having difficulty seeing through it.
opaque
a. １．不透明的，不透光的；２．难理解的，晦涩的
a: women in the old days were frequently oppressed by their husbands.
b: i am glad that times are changing.
oppress
vt. １．压迫，压制；２．使（心情等）沉重，使烦恼
a: you would like the blue car?
b: no, i think i’ll opt for the red one.
opt
vt. (for) 选择，挑选
a: the weather will be wonderful tomorrow.
b: you are always filled with optimism .
optimism
n. 乐观，乐观主义
a: i study at my optimum between eight and ten in the morning.
b: oh, i work best in the evenings.
optimum
a. 最合适的，最优的，最佳的
a: where did you get the apples?
b: i picked them in the orchard down the road.
orchard
n. 果园
a: i was in a serious car accident last year.
b: that must have been a terrible ordeal .
ordeal
n. 苦难经理，折磨，煎熬
a: i love studying science.
b: i orient more towards the arts.
orient
vt. １．使适应，使熟悉情况（或环境等）；２．（to ,toward）使朝向，以．．．为方向（目标）
n. 东方，亚洲（尤指远东），东半球
a: oriental cuisine is my favourite.
b: yes, i also love chinese food.
oriental
a. 东方的，东方人的，东方文化的
a: i was unable to find my orientation in the city.
b: you should have carried a map with you.
orientation
n. １．方向，目标，方位；２．熟悉情况，适应，情况介绍
a: from where does the guitar originate ?
b: well, there are many types of guitar, so probably many countries.
originate
vi. (in,from,with) 起源于，来自，产生
vt. 创造，创始，开创
a: that is a beautiful ornament beside the tv.
b: thanks, it was a gift from a friend.
ornament
n. １．装饰品，点缀品；２．装饰，点缀
vt. 装饰，点缀，美化
a: i was an orphan until the age of seven.
b: goodness, do you know what happened to your parents?
orphan