Beethoven established himself as the greatest composer ______.

A．he felt good in his romantic relationships
B．he realized that his hearing was compromised
C．he felt inadequate to create more musical pieces
D．he was very low in spirits

A．They could drive the insects away.
B．They could keep the plants well-watered.
C．They could make the plants grow faster.
D．They could build devices to trap insects.