雷达干扰可分为（）。
A.压制性干扰
B.欺骗性干扰
C.有源干扰
D.无源干扰
参考答案：C, D
芜荑的药用部位是（）
A.根
B.叶
C.花
D.茎
E.加工品
There _____ a large amount of new students in our school this year.[ ]
A. is
B. are
C. be
D. were
