问题
选择题
While the soldier’s idea was interesting, the system was too difficult to be ____.
A．of practical use
B．practical usefully
C．practice use
D．practice used
答案
答案：A
考查use的形容词性的用法，根据句子结构可知此处填的应当是形容词，或者名词，即practically useful,=" of" practical use