113 Our research team _____ on developing a more efficient battery for the past two years.
(A) works
(B) is working
(C) has been working
(D) worked
答案:登入後查看
統計: A(24), B(51), C(752), D(100), E(0) #3772621
統計: A(24), B(51), C(752), D(100), E(0) #3772621