问题
选择题
When the shy girl couldn't answer the teacher's questions, she felt _____ and uncomfortable. [ ]
A. tough
B. awkward
C. sceptical
D. curious
答案
答案:B
When the shy girl couldn't answer the teacher's questions, she felt _____ and uncomfortable. [ ]
A. tough
B. awkward
C. sceptical
D. curious
答案:B
为了节能和环保,一些公共场所使用光控开关控制照明系统,光控开关可采用光敏电阻来控制,光敏电阻是阻值随着光的照度而发生变化的元件(照度可以反映光的强弱,光越强照度越大,照度单位为Lx)。某光敏电阻Rp在不同照度下的阻值如下表:
照度(lx) | 0.2 | 0.4 | 0.6 | 0.8 | 1.0 | 1.2 |
电阻(kΩ) | 75 | 40 | 28 | 23 | 20 | 18 |
根据图线求光敏电阻值为30kΩ时照射光的照度为 lx。