Autofocus lenses use what to determine the correct focus?

Which principle of design is in primary use in this sculpture?

What is the most famous racetrack in america?

Discussion board 5 - the romantir areanocturne, op. 9 no 2 solo piano - chopin (peatured listening p 778)when you listen to this piece, what does it make you think of and how does it make you feel? what do you think "nocturne" means? is that an appropriate title for this piece? the piano uses rubato throughout - what effect does that have on the performance? do you think the use of rubato enhances the performance, or would you rather hear a steadybeat throughout the piece? after you post your answer, read and respond to the posts of at least two other classmates.