Recommended by FagnerLSantos
"THEN" and "THAN"
"Then" relates to time. "Than" is used for comparison. Ex.: First, we'll have lunch, and then we'll go for a walk. He is more experienced than I am.
"ENSURE" and "INSURE"
"Ensure" means to guarantee or make certain. "Insure" refers to obtaining insurance coverage. Ex.: Please ensure the door is locked. We need to insure our new car.