when first ___to the market .the toys didn’t attract much attention.a.introducingb.introducedc.was introducedd.being introduced理由啊

when first ___to the market .the toys didn’t attract much attention.a.introducingb.introducedc.was introducedd.being introduced理由啊
when first ___to the market .the toys didn’t attract much attention.
a.introducing
b.introduced
c.was introduced
d.being introduced
理由啊

when first ___to the market .the toys didn’t attract much attention.a.introducingb.introducedc.was introducedd.being introduced理由啊
选 B
过去分词表示被动完成

B

B
过去分词做时间状语