We should take good care of the elderly, as they are ______ to the sudden change of weather.
He met his previous teacher ________ at abroad.
Tom, ______ yourself .Did you forget the school rules?
He is the only one of the students who ______a winner of a scholarship for three years.
Though having lived abroad for years, many Chinese still ______ the traditional customs.
The president spoke at the meeting for nearly an hour without _______ his notes.