179. His appearance was completely unexpected.
→His appearance 

178. The riddle of the missing heiress has been solved.
→The police 

177. Gunman kills 3 people in Bank Drama.
→A man 

176. Amanda has improved a lot this term. (PROGRESS)

175. Come on Thursday or Friday. It’s all the same to me.
(DIFFERENCE)

174. I know you are hiding something from me. (BACK)

173. We’ve decided to leave early tomorrow morning. (SET)

=172. We have an emergency electricity supply in case we are cut
off. (BACK)

171. Interrupting when someone is speaking is rude. (CUT)

170. The numbers of cars on the roads must be reduced. (DOWN)