The number 13 is considered an （lucky） number in some Western countries．Many hotels and tall buildings don't have a 13th floor or a Room 13．
School bus （safe） is a big problem in China．
Sometimes，a person's whole life is （easy） changed by something unexpected．
Blue is a （peace）color．People often feel quiet in blue rooms．
Brush your teeth at least （two） a day：in the morning and before bedtime．