11.   Sizes vary, but usually the viewing area is between the size of a matchbox and, say, a playing card.

12.   Sizes vary, especially with imported rugs.

13.   The screen size varies widely.

14.   The size can vary depending on the quantity of leaves.

15.   The specific watershed size varies for different lakes and rivers, depending on topography and other factors.

16.   Size can vary widely.

17.   The text size will automatically vary with the frame.

18.   Their size varies as well.