They succeeded at last after adopting an＿ ＿method.C.effective D.efficient这两个当中不知道选谁?I paid a visit to him last night.We had a chat ＿＿cofff.A.with B.in C.over D.by 希望能说明原因,

They succeeded at last after adopting an＿ ＿method.C.effective D.efficient这两个当中不知道选谁?I paid a visit to him last night.We had a chat ＿＿cofff.A.with B.in C.over D.by 希望能说明原因,
They succeeded at last after adopting an＿ ＿method.
C.effective D.efficient这两个当中不知道选谁?I paid a visit to him last night.We had a chat ＿＿cofff.A.with B.in C.over D.by 希望能说明原因,

They succeeded at last after adopting an＿ ＿method.C.effective D.efficient这两个当中不知道选谁?I paid a visit to him last night.We had a chat ＿＿cofff.A.with B.in C.over D.by 希望能说明原因,
1c 很多情况下这两个词可以通用,但 efficient 多指人高效的,effective多用于物
2c 边聊天边喝茶就用over记住就可以了