根据句意,用所给单词的适当形式填空。
1.Weallknow______________(pollute)waterdoesharmtoourhealth.
2.Ihavereadfive (twelve)ofthisbook.
3.Ifyouareinabluemoodyoucandoyourhobbiestocheer (you)upboys.
4.Totellyouthe (true)Ifeltsadwhileyouwereaway.
5.Thechildrenheardthe (frighten)shoutandlookedateachotherinfear.