这句子对吗

对
It is ... that
强调句型

把It is ... that去掉这句话就是

it happened two weeks ago .

应该是it happened two weeks ago

错的.
it happened two weeks ago.

强调时间 It was two weeks ago when it happened.
叙述事件 it happened two weeks ago

right!

it was two weeks ago that it happened.
是强调句式。
如何判断强调句式？ 用还原法试一试：
it happened two weeks ago.
it is/was+ 被强调成分+ that + ...
又有如; Tom saw a girl in the street yesterday.
it was Tom that saw a girl in the street yesterday.
it was a girl that Tom saw in the street yesterday.
it was in the street that Tom saw a girl yesterday.
it was yesterday that Tomsaw a girl in the street.