Which of the sentences from
the passage is a main idea?
Click or tap the correct answer.
These instruments have since
A been nicknamed
"squeezeboxes."
1800 to 1850 was also the era
B when music was being
shaped by the valve.
Pieces of a valve mechanism
C block or open the main
column of air.
Heinrich Stölzel invented the
D earliest version called a
piston valve.