prevent

block, bar, hinder, obstruct, prevent, hamper

这些动词均含有“阻止、阻塞”之意。
block: 语气强烈，指有效堵住了通道，使人或物无法通过。
bar: 含义与block很接近，指阻塞通道或禁止出入，但有暗示不用障碍物的阻止或禁止。
hinder: 语气较轻，多指阻碍、拖延人或事，强调使进展速度缓慢下来。
obstruct: 正式用词，语气强，多指以干扰或设置障碍的方式阻碍交通，使不能自由畅通。
prevent: 含义广泛，指采取预防措施或设置障碍去阻止某人或某事。
hamper: 侧重因受到约束或阻碍而造成的行动困难。

动词 prevent:

1. keep from happening or arising; make impossible
   同义词：forestall, foreclose, preclude, forbid
2. prevent from doing something or being in a certain state
   同义词：keep

1. The government tried to prevent the diminution of resources.
   政府试图阻止资源的减少。
2. Props were used to prevent the roof collapsing.
   用了一些支柱以防止屋顶塌落。
3. The car came to a halt just in time to prevent an accident.
   汽车及时停下，避免了一场车祸。
4. The policy is designed to prevent the predominance of one group over another.
   该政策旨在防止一些人压制另一些人。
5. They painted a coat of paint to prevent the oxidation of the ship by seawater.
   他们刷了一层油漆以防止船只被海水氧化。
6. Strove to prevent our courage from turning into bravado.
   努力预防我们的勇气变成一种虚张声势
7. These regulations are intended to prevent accidents.
   这些规章制度旨在防止事故发生。
8. What can we do to prevent the disease spreading?
   我们能做什么来防止这种疾病蔓延呢？

pre.vent

v.（动词）
pre.vent.ed,pre.vent.ing,pre.vents
v.tr.（及物动词）
To keep from happening:
预防：使防止发生：
例句：
took steps to prevent the strike.
采取步骤避免罢工

To keep (someone) from doing something; impede:
阻碍：使（某人）不做某事；阻挠：
例句：
prevented us from winning.
阻挠我们获胜

Archaic To anticipate or counter in advance.
【古语】 预先应付：事先预料或遇到
Archaic To come before; precede.
【古语】 在…之前：在…之前来；先于
v.intr.（不及物动词）
To present an obstacle:
阻挠，阻止：呈现出阻碍：
例句：
There will be a picnic if nothing prevents.
如果没有特别的情况，我们将举行野餐

来源：
Middle English preventen [to anticipate]
中古英语 preventen [预料，预期]
from Latin praevenore praevent-
源自 拉丁语 praevenore praevent-
prae- [pre-]
prae- [前缀，在…之前]
venore [to come] * see g w3-
venore [来] *参见 g w3-

【引伸】
prevent.abil.ity 或
prevent.ibil.ity
n.（名词）
prevent.able 或
prevent.ible
adj.（形容词）
prevent.er
n.（名词）
<参考词汇><同义词>prevent,preclude,avert,obviate,forestallThese verbs mean to stop or hinder something from happening, especially by advance planning or action.
这些动词是指停止或阻挠某事的发生，尤指以预先的计划或行动来阻挠
Prevent implies anticipatory counteraction:
Prevent 指预先阻止：
例句：
.The surest way to prevent war is not to fear it. (John Randolph).Topreclude is to exclude the possibility of the occurrence of an event or action:
.阻止战争最有把握的方法是不要害怕. （约翰·伦道夫）。Preclude 指排除某事或行为发生的可能性：

例句：
.a tranquillity which . . . his wife`s presence would have precluded. (John Henry Newman).Toavert is to ward off something about to happen:
.他妻子的出现使宁静成为不可能. （约翰·亨利·纽曼）。Avert 是指阻止将要发生的事情：

例句：
Only quick thinking on the pilot`s part averted a disastrous accident.
只有这位飞行员的机智才能阻止这样可怕事件的发生。

Obviate implies that something,such as a difficulty, has been anticipated and disposed of effectively:
Obviate 暗指某物，如困难已经被预料到且被有效地排除掉：
例句：
.the objections . . . having . . . been obviated in the preceding chapter. (Joseph Butler).
.反对意见…已经…在前一段时间被排除了. （约瑟夫·巴特勒）。

Forestall usually suggests anticipatory measures taken to counteract, neutralize, or nullify the effects of something:
Forestall 通常指预先采取措施来消除，中和或抵消某事的后果：
例句：
We installed an alarm system to forestall break-ins.
我们安装了一套警报系统来预防小偷的闯入