18 had better （not） do sth。

　　你最好把收音机的声音关小点。你没看见妈妈正在睡觉吗？

　　You had better turn down the radio。 Can’t you see mum is sleeping？

　　我们在饭馆里最好保持安静。

　　We’d better keep quiet in a restaurant

　　你最好不要吃太多快餐。

　　You’d better not eat too much fast food。

19 help sb。 （to） do/help sb.with

　　她经常在妈妈不在家时帮妈妈照看小妹妹。

　　She always helps her mother look after her little sister while her mother is away。

　　我哥哥过去常常帮妈妈做家务。

　　My brother used to help Mum with the housework

　　我经常帮同学们打扫卫生。

　　I often helped my classmates do the cleaning。