Of the seven days in a week, Saturday is said to be the most popular ___ for a wedding in some countries.
Under no circumstances _______ the difficulties when they were on an expedition to the Antarctic.
In the city, I saw so grand a National Day celebration _______ I never dreamed of.
If only I _______ more confidence in the English speech contest held last week!
According to the school rules, no child _______ be allowed out of the school during the day, unless accompanied by an adult.
It was not until 1911, _______ the first vitamin was identified, _______ people realized the importance of it.