______ the students found the soldier's
题型：选择题
问题：
______ the students found the soldier's idea interesting, the system was too difficult to be
of practical use. [ ]
A. While
B. Unless
C. As soon as
D. Even if
______ the students found the soldier's idea interesting, the system was too difficult to be
of practical use. [ ]
A. While
B. Unless
C. As soon as
D. Even if