【简答题】Exercise: Choose the proper phrases in its appropriate form to fill each blank in the following sentences. hold out hold back hold down hold off ■ The dam was not strong enough to 1 the flood wa...
【判断题】Hydropower systems build pressure either by containing the water behind a dam, or within a pipe that runs down a hill. The weight of the water behind the dam or in the pipe creates pressure at the bot...
【简答题】听下面一段对话,回答1-4题。 1. What do we learn from the passage? A. More can be done to reduce the damage of earthquake B. Earthquakes always cause serious damage C. Nothing can be done to reduce the damage of e...