1 They have to go (across) the river to school every day.
在动词go后要填介词形式.
2 Are you afraid (to speak) in front of many people?
be afraid to do,害怕做某事.
3 The (villagers) want to have a bridge.
主语是人（村民们）,动词原形说明是复数.
4 It's not easy for many students in a village（to get) to school.
it's +形容词+to do,做某事如何.
5 I'm (truly) sorry about it.
填副词,修饰形容词sorry.