There ______ a lot of nice food for you. [ ]
A. is
B. are
C. have
D. has
答案:A
()适宜于加入缓凝剂。
A.5℃以下施工的混凝土
B.有早强要求的混凝土
C.大体积的混凝土
D.蒸养混凝土
HF天线耦合器有问题,在HF收发机前面板上启动自检:()
A、当自检完成后,KEY INTERLOCK灯一直亮;
B、当自检完成后,KEY INTERLOCK灯灭;
C、当自检开始前,KEY INTERLOCK灯亮;
D、不能进行自检