1) 很重要的一个区别，是“真的是”和“像是”的区别。

• He worked as (*like) a waiter for two years.他干了两年的招待员。
• Please don't use that knife as (*like) a screwdriver.这把刀子请不要当作改锥使用。
• A crocodile starts life as (*like) an egg.鳄鱼的生命开始于卵。

试比较：

• As your brother, I must warn you to be careful.身为你的哥哥，我必须警告你要小心。
• Like your brother, I must warn you to be careful.我必须像你的哥哥一样警告你要小心。

但是如果前后文（尤其是动词）已经明确指出了并非“真的是”，习惯上反而要用 as 而不用 like；例如：

• She disguised herself as (*like) a boy.她假装成男孩。
• Upon a closer look, authorities realized the "student" trying to take the exam was a male masquerading as (*like) a girl.负责人员再仔细一看，原来那个企图应考的“学生”，是个假装女孩子的男子。

2) like 在美国英语中常常可以用来代替 as if 或 as though（从句中不用虚拟语气而用直陈语气）。

• Like that matters.仿佛这一点有多么重要似的。
• He talks to me like I was his dog. 他把我当成他的狗那样对我说话。Like I've been eating Styrofoam. (Dan Brown, Angels and Demons, p.15)好像我一直在吃着保丽龙泡沫塑料似的。

有时后面接上的不是句子而是名词成分加上动词现在分词 -ing，也表示“仿佛”的意思。

• It was like Nero offering a brilliant water-and-sewage plan for Rome in the midst of the fire. (Time, May 24, 2004, p.25)正如尼罗在火烧罗马城之际提出了一个出色的供水排水方案那样滑稽。
• But it doesn't seem like he has anyplace else to go.但是看来他似乎没有别的地方可去。