This makes it more difficult for students to buy papers from companies that some call "plagiarism mills" or "essay mills."

VOA: special.2009.04.23

This makes it more and more difficult for them to make friends and more likely that society will reject them.

VOA: special.2010.01.06

This makes it more difficult for the body to effectively use the same amount of oxygen as it would on the ground.

VOA: special.2009.07.14

And,this constant movement of population also affects the humanitarian workers as it makes the planning and the delivery of aid much more difficult because we cannot predict where the people are going or if they are coming back."

VOA: standard.2009.06.21