80. World scientists and experts are on the ________________________ for effective vaccine against COVID-19. (LOOK) 81. Everyone, the old and the young alike, is advised to adopt a positive ________________________ on life. (LOOK) 82. Everyone is supposed to live and act in ________________________ to the law. (OBEY) 83. He is always ________________________ to his fathers wishes, which is really annoying. (OBEY) 84. For most of the students the question was too tough or ________________________. (ANSWER) 85. By mistake, some letters were left ________________________ and she was fired. (ANSWER) 86. According to the contract, you are under no ________________________ to pay the rent in advance. (COMPEL) 87. Is military service ________________________ in your country? (COMPEL) 88. Everyone feels the ________________________ reason for protecting their cradle, the Earth before it is too late. (COMPEL) 89. She bites her nails all the time in the exam. It is a sign of ________________________. (NERVE) 90. We were all amazed by the ________________________ of the little girl. (NAIVE)