When your parents haven’t ____your letter for a long time,they will worry about you.
76. He cut the apple ________, and gave the big to his little sister.
75. Taiji boxing is good _____ health, so the old man began to practise it ten years ago and now he is good _____ it.
74. We went _____ our plan carefully before we carried it out.
73. It is not right _____ a person who is _____ trouble.
72. We couldn’t read the notice on the board because several people were standing _______ it.