前3个动词跟from 连用时，意思一样，都是“阻止”，这是由from 的词义决定的。只有protect 是“保护”。

1. keep 是否与from 连用，意思正好相反，例如：

keep the boy running around：让男孩到处跑。

keep the boy from running around：不让男孩到处跑。

2. prevent sb. from doing 和stop sb. from doing，省去from，意思不变。因为动词本身就是“阻止”，有没有from 无关紧要。这也从反面证明了，keep 用不用from 会产生相反的语义，因为keep 动词本身是“继续保持”，不是“阻止”。

protect...from/against保护......免受......（之害），虽然prevent...from,keep...from以及stop...from有时也含有这种意义，但其主要意思是表示“阻止或防止”。单项选择题通常是选择“最佳答案”而不是选择“正确答案”，所以根据题意选项D（protect）是最佳的。以下各句均表示“保护”之意，你再仔细体会一下是用protet好还是用keep好？

She wore a hat to protect her skin from the sun.她戴帽子保护她的皮肤不受日晒。《21世纪英汉汉英双向词典》

He raised his arm to protect his face from the blow.他举起手臂护住脸以免被拳击中。（张道真《英语常用动词用法词典》）

You need warm clothes to protect you against the cold. 你需要穿暖些以免着凉。《牛津高阶英汉双解词典》

Many manufacturers have policies to protect themselves against blackmailers.许多厂家都购买了保险，以防遭到敲诈。《柯林斯高阶英汉双解词典》

Net the fruit trees to protect them from birds.用网盖住果树以免遭鸟害。《简明英汉词典》

A line of forts was built along the border to protect the country against attack.在边界沿线构筑了堡垒, 以防国家受到攻击。《现代英汉综合大辞典》

(1) protect sb from sth保护/防护某人不受某事影响/伤害

So, what can women do to protect themselves from heart disease?

那么，女性怎样做才能使自己不得心脏病呢？

(2)keep sb from doing sth阻止/防止/阻碍某人做某事

Embarrassment has kept me from doing all sorts of things.

我总是害怕受窘，什么事都不敢去做。

He kept her from being lonely.

他不让她感到孤独。

(3)prevent sb from doing sth 阻止/制止/阻碍某人做某事

He said this would prevent companies from creating new jobs.

他说这将使公司无法创造新的工作机会。

Its nationals may be prevented from leaving the country.

其国民可能会被禁止出境。