根据句意，用所给动词的适当形式填空。
86. We are told___________(not laugh) at those in trouble.
87. When I was young, my grandfather told me that the sun________(rise) in the east.
88. I don’t like the boy because he keeps_________ in class. (talk)
89. This kind of shoes ___________ ( sell ) well.
90. I hope you __________ ( regard ) me as your friend forever.