Why did regionalism become so popular in the U.S. during the Great Depression().

A.Because the paintings sold very well.

B.Because it helped strengthen people’s faith in their country.

C.Because people liked to live in the country at that time.

D.Because it helped recover the economy.

（）对革兰氏染色阳性的细菌作用较大，但是对阴性细菌作用则较小。

A.链霉素

B.青霉素

C.抗菌素

D.庆大霉素