美国ARCO权威托福参考词汇:O字头

O
oath
n.誓言, 宣誓, 诅咒 a solemn attestation of the truth or inviolability of one’s words
obstacle
n.障碍, 妨害物 something that impedes progress or achievement
ominous
adj.预兆的, 恶兆的 being or exhibiting an omen : PORTENTOUS;
on the spot
adv.当场, 在危险中, 处于负责地位
operation
n.运转, 操作, 实施, 作用, 业务, 工作, 手术

option
n.选项, 选择权 the power or right to choose : freedom of choice
outlawe
n.歹徒a lawless person or a fugitive from the law
逃犯 a person excluded from the benefit or protection of the law
v. 宣布...为不合法to deprive of the benefit and protection of law : declare to be an outlaw
overlap
v.(与...)交迭 to extend over or past and cover a part of
overwhelm
vt.淹没, 覆没 to cover over completely : SUBMERGE 颠覆，推翻UPSET, OVERTHROW