To use the _____ only when it is necessary.
举一反三
- When will college students curb their spending and only buy what is necessary?
- In a presentation, we should only use visual aids if they are necessary to maintain interest and assist comprehension.
- Using the mother tongue only when it’s necessary helps to make instructions effective.
- The page number is not necessary to cite, when we want to use main idea but not the exact sentence.
- Only when the factories use electricity, they put greenhouse gases into the air.