Here are the rewritten sentences:

78. Trouble is what they’ll cause.
79. It’s often said that love and hate are almost indistinguishable.
80. She’s very wealthy; she can buy anything she desires.
81. There is a likelihood of a temperature rise in the next century.
82. You need to acknowledge that she has left you.
83. I felt completely at a loss for words.
84. They reached the station with just a minute to go.
85. He received a three-year prison sentence.