按照句子结构的语法性，在下面空格处填入一个适当的词语或使用括号中词语的适当形式填空
Unless _________ (invite), I won’t attend their wedding.
We spent an ___________ (enjoy) weekend.
He noticed all the room ____________ (break) into at the case spot.
Your graduation paper must ____________ (submit) by 10am.
She is really a __________ (gift) biochemist.
Hardly had she arrived home ________ it began to rain heavily.
At first, she worked as an ____________ (assist) to a famous journalist.
After the film was over, people went home ___________ all directions.
If you don't go swimming tonight, __________ will I.
The child held his mother’s arm _____________ (firm) when he saw her.
Those books ____________ (buy) on the Internet are usually best-sellers.
We must be strict ___________ ourselves.
_____ seemed that the water was to blame.
I find it difficult ____________ (learn) English well.
Doctors are trying a new ________ (treat) for cancer.