1 . --I called your office at about ten this morning, but there was no reply.
--Oh, that was probably ________ I was paying a visit to a friend in hospital. (用适当的词填空)

2 . I always read newspapers backwards because the back pages are ________ the sport is. (用适当的词填空)

4 . This is ________ many people fall short: You should wash your hands for at least 20 seconds. (用适当的词填空)

5 . This is ________ my father has taught me—to always face difficulties and hope for the best. (用适当的词填空)

6 . As John Lennon once said, life is____happens to you while you are busy making other plans. (用适当的单词填空)

7 . By boat is the only way to get here, which is _______ we arrived. （用单词适当形式填空）