make sure
Make sure (phrase) means to take action to confirm that something is true or that something happens as intended. Example: “Make sure the door is locked before you leave.”
How to use make sure
Learner’s notesIn plain EnglishTo check or do something so that you know it will definitely happen.
Neutral and very common in both speech and writing; "ensure" is preferred in formal documents.
After "make sure", use a present-tense verb even when talking about the future: "Make sure you arrive by six", not "will arrive".
Fill the gap
Can you complete this real example?
_____ the door is locked before you leave.