<單選題>
______ machines have been used to pick fruits for a long time, they were not used on strawberry farms until several years ago.
(A) Although
(B) Because
(C) Before
(D) If
答案
______ machines have been used to pick fruits for a long time, they were not used on strawberry farms until several years ago.
(A) Although
(B) Because
(C) Before
(D) If