printed, this science fiction will be popular among the students.
A. Before
B. Unless
C. Although
D. Once
网友回答
A. Before
B. Unless
C. Although
(答案→)D. Once
解析：考查连词的用法。Before在……之前，Unless除非，Although虽然，Once
一旦，句意：一旦这部科幻小说被印刷，它将在学生中很受欢迎。故选Once，Once后省略了it is 。