垫板和扫地杆的最大距离不应超过()m,横向扫地杆亦应采用直角扣件固定在紧靠纵向扫地杆()的立杆上
A.0.3,下方
B.0.2,上方
C.0.3,上方
D.0.2,下方
参考答案:A
Cl-、Br-、I-等离子都可在HNO3介质中与AgNO3起反应生成沉淀,但()在加氨水后不溶解而与其他离子分离.
A、AgCl
B、AgBr
C、AgI
The computer system____suddently while he was searching for information on the Internet.
A.broke down
B.broke out
C.broke up
D.broke in