适当形式填空（共5分）
He promised his father that he _______________(give) up smoking this year.
I did what I can _____________(help) my brother with his English study.
The accident suddenly_______________(happen) while the lights were changing to red.
Everyone agreed that we should stop the factories ______________(pour) the dirty water into the river.
They think you’d better not ____________(join) this club this year.