Words and phrases:

certain

for certain

on one’s own

warn

might (may)

house+work=housework

Grammar:

attributive clause（定语从句）

relative pronouns（关系代词）

antecedents（先行词）

当先行词指人时，关系代词用“who/that”；

当先行词指物体时，关系代词用“which/that”。

关系代词在从句中的成分：主语，宾语

关系代词的省略：在从句中作宾语时

Possibilities:

may

might

perhaps

probably

maybe

Sentences:

The scientist also warns that if we are lucky, they might treat us as we now treat our pets.

Perhaps there will be a war between human beings and robots.

In a few years, perhaps robots will think on their own, just as people use their brains and act for themselves.

However, once robots can think for themselves, problems may appear.