71. Sorry, it’s too late to ________(取消) your order. Your order has been sent on the way.
72. It’s necessary to think of some ________ (安全) tips to protect ourselves against crime.
73. I just don’t know why the engineer has so many ________(敌人).
74. The ________ (发现) of America is made by Columbus.
75. Life is too busy, and sometimes it will let me breathe _________(呼吸) heavily.