Whether enough blood is donated could be a(an) ________ of life and death for the accident victims.

Would you please ______ your statement again? I don’t understand what you were saying.

 -- Why was the driver taken to the police station last night? -- Because he refused to ______ to a blood-alcohol test and attacked the police.

I used to go to the gym three times a week, but I don’t _______ any more.

Knowing what colors look good _______ your skin is of great importance when you buy clothes.