Why do plants need nitrogen?

Whose work is most likely to be part-time and at several locations? а. physical therapistb. sports physicianc nutritionistd group fitness instructor

World class speed skaters can skate a 3,000-m course in about 4 minutes. what is their average speed for this course. a. 12.5m/s b. 1.33m/s c. 13.3m/s d. 1.25m/s

What percentage of light hits earth's surface directly?