Swimmers must be very strong in order to build up speed because of the high resistance (阻力)of the water. Runners,__________, must struggle against the heavy resistance of the air and ground.
180. There is a _____ of understanding between them. Otherwise, they will be good friends.
179. In China, the majority of men earn their living by manual ______.
178. There are four basic _____ of blood in the human body. What do you belong to, A, B, AB or O?
177. You should turn to Mrs. Green. She is the key figure in the company. The underlined part probably means _____.
176. Three times the accused was brought to court for trail, he was sentenced half a year’s imprisonment by the _____.