Why are house keys usually made of metal rather than glass, wood, or fabric what common material or flip-flops usually made of? why? what other materials work? Why or why not?

because if not metal than other things like glass wood or fabric would break or not be suitable for the key hole.

Explanation:

flip flops are made of plastic.

the truman doctrine was an american foreign policy whose stated purpose was to counter soviet geopolitical expansion during the cold war. it was announced to congress by president harry s. truman on march 12, 1947, and further developed on july 12, 1948, when he pledged to contain threats to greece and turkey.

substitution is the answer in this case