ensure

"The condition for getting a raise at work is meeting your quarterly targets. "

"My friend told me there was something in the box, but I didn't know what it was yet. "

"My daughter's teacher is very kind and helpful. "

"The teacher ensured her students that the test would cover only the topics they studied in class. "

"Do you need a gift for that special someone?"

"Can you give me a guarantee that he will be fit for the match?"

"Except for one or two days a year, he usually walks to work."

"She gave a studied reply."

"if I make a promise, I always stick to it;  he broke his promise"

"The student made a pledge to study harder for the upcoming exam. "

"The certain success of the project was a relief to the team. "

"The teacher assured the students that the exam would be graded fairly. "