问题
选择题
— Lucy looks blue today.
— Yes, but I don't know what it is________makes her so upset. [ ]
A. as
B. what
C. that
D. which
答案
答案：C
搜题请搜索小程序“爱下问搜题”
— Lucy looks blue today.
— Yes, but I don't know what it is________makes her so upset. [ ]
A. as
B. what
C. that
D. which
答案：C
三瓶失去标签的无色溶液分别是稀盐酸、碳酸钠溶液、氢氧化钡溶液，某同学将其任意编号为A、B、C，且各取少量进行分析，得到相关的实验记录（如下表），
| 实验内容 | 观察到的现象 |
| A+B | 有气泡产生 |
| A+C | 有白色沉淀产生 |