Describing Data

To Increase
When something goes up, it increases.
Sales have increased by 15%.
To Decrease
When something goes down, it decreases.
Costs have decreased by 10%.
To Remain Stable
If something remains stable, it neither increases nor decreases.
The company's sales remained stable last year.
To Fluctuate
When something fluctuates, it increases and decreases.
This chart shows how much sales are fluctuating.

fluctuate [ˈflʌktʃueɪt]
v. (大小、数量、质量等) 波动; (在…之间) 起伏不定;

Exercises beyond the original
Their number of customers has increased.
The price has remained stable.
Their profits fluctuate greatly from year to year.
Our business costs have remained stable over the past two years.
Listen and Repeat
The price has remained stable.
Read the Sentence
The product has become popular, so sales have increased.