根据句意和首字母提示补全单词。
66. Mr. Smith can o_____ his guests some coffee or tea when they come to his home.
67. Today, everyone o_____ to be a greener person.
68. I felt a sharp pain in my c_____.
69. He is the s_____ of person who only cares about money.
70. We must remember that n_____ of us is infallible (永无过失的). We all make mistakes.