28. The book was written _____ careful observations and detailed studies.
Britain’s first and only female prime minister , Margaret Thatcher, died on April 8 at the age of 87, after suffering a stroke (中风), _______ has aroused a flood of comments about her political life again.
I missed the last bus and had no money for a taxi; so I could do nothing but_______ home last night.
Who do you think will _______ since the president has resigned?
--How was your weekend, Rose? --Awful! This was the first time I ________ alone at home, bored to death.
Many citizens urged their government to take measures to cut _______ their carbon emission to reduce greenhouse effects.