He ran so fast that I couldn't catch up with him.
他跑得太快赶不上他.

说得对.这确实是一个搜趣网“主系表”句型.当表语是表示人的心理状态的形容词（也可以是表心理状态的动词的分词,大多是过去分词）时,后面接从句,不定式短语或介词结构等说明心理状态产生的原因.
如；I'm sorry to have deRTnwPkept you waiting fo//www.souquanme.comr a long time.
He is proud that his daughter has been admitted to a famous university.

it's time that we begin our work.(it's time .....是“正是做什么的时间”的意思)
it's important that this application is filled.
it's said that Mike has been killed.（it's said是“据说。。。。”的句型）
it's working that we persuade him.(我们劝说他似乎正在起作用)——这里要注意，不及务动词是没有被动态的，因此只能够用ing形势

She said so slightly that I couldn't hear clearly.
She cried loudly that we could hear in the distance.
She worked well that I admired her.