Languages use the same words over and over. Be sure you are using the most important function words so that your students will know and be able to use them.
You can find a set of Spanish function words here. They are about the same in every language, so take a look even if you do not teach Spanish. Teaching these function words as lists would be contrary to acquisition-based teaching, so I wouldn’t use these for graded tests, but from time to time as an indicator of what students are acquiring through the school year, they can be useful. If students are weak in some of them, you can purposely use those words until they are up to speed.