to be uneasy/anxious/nervous/worried about something; to worry; to be like a cat on hot bricks
What worries you most?; what most worries you?
Don't worry, I am only pretending!
Are you nervous about the exams?
to take care of ...; to look after ...; to see to something; to take charge of ...
You can't look after the house on your own, get some help/get someone to help
To look after number one