Dic: make demands on, make demands of

• I had no right to make demands on his time.
• Please don't make demands of everyone in the shop.
• The boss is making a lot of demands on the new machinery.

■ PHRASE : V inflects, usu PHR on n | If someone or something makes demands on you, they require you to do things which need a lot of time, energy, or money.

■ Dic: the demands of something, demands on you

■ make demands of someone or something(and make demands on someone or something) : to expect someone or something to do something or act in a particular way.

... Cobuild, http://idioms.thefreedictionary.com/make+demands+of

■ demands [plural] : the difficult, annoying, or tiring things that you need to do, or a skill you need to have.

• demands of: the demands of modern life.
• demands on: The curriculum makes great demands on the teacher. There are heavy demands on people's time these days.
• place/put demands on/upon somebody/something: the increased demands placed on police officers.

■ demands [pl.] ~ of sth, ~ on sb | things that sb/sth makes you do, especially things that are difficult, make you tired, worried, etc.

• the demands of children / work.
• Flying makes enormous demands on pilots.

... LDOCE, OALD