Many students’ failure ____ their carelessness in every examination.
I found the island a wonderful place for our experiments _______ the hot weather.
He usually goes to work by bike _______ it rains.
She knew nothing about his journey _______ he was likely to be away for three months.
“How did the robber get in?” “______ an open window on the first floor.”
_______ reading the letter, what has he done?