问题
选择题
The number of workers in this factory _____ 1,500.
A number of them _____ from the countryside. [ ]
A. is; are
B. are; is
C. is; is
D. are; are
答案
答案：A
搜题请搜索小程序“爱下问搜题”
The number of workers in this factory _____ 1,500.
A number of them _____ from the countryside. [ ]
A. is; are
B. are; is
C. is; is
D. are; are
答案：A
下列各组离子，在指定的环境中能够大量共存的是[ ]
指定环境 | 能够共存的离子 | |
| A. | 滴加酚酞显红色的溶液 | K+、 S2-、 SO32-、NO3- |
| B. | 有HCO3-存在的无色透明溶液 | Na+、K+、Cl-、Al3+ |
| C. | 水电离的c（H+）=10-12 mol/L的溶液中 | Cl-、CO32-、NO3-、NH4+ |
| D. | 使石蕊变红的溶液中 | Fe2+、MnO4-、NO3-、SO42- |