87．___________________(為了確保他參加會議)，I called him up in advance.
88．The significant museum________________(據(jù)說建成于)about a hundred years ago.
89．There would be no life on earth ____________________ (沒有地球獨特的環(huán)境)。
90．______________________________(給游客印象最深的)was the friendliness and warmth of the local people.
91．They requested that ___________________________ (我借的書還回圖書館) by next Friday.
