It's said that the agreement______ between the two companies last month will become effective from May 1st.
【正确答案】 B
【答案解析】解析:本题考查的是分词作定语。用过去分词表示agreement与sign之间的被动关系,相当于一个定语从句,即the agreement which was signed。因此B项为正确答案。