61. 1. useless2. active
3. harmful4. changeable
62. 1. factor2. energy
3. method4. manner
63. 1. studied2. passed
3. dropped4. failed
64. 1. however2. therefore
3. in addition 4. as a result
65. 1. action2. behavior
3. routine4. performance
66. 1. waste2. enjoy
3. spend4. collect
67. 1. fearful2. durable
3. destructive4. threatening
68. 1. throw2. direct
3. point4. shoot
69. 1. awful2. impatient
3. powerful4. aggressive
70. 1. sadden2. worsen
3. weaken4. Lengthen