【简答题】从方框中选出适当的句子补全对话。 A: Hi, Sally. I’m going to the USA as an exchange student. B: Great. A: But I don't know much of the customs and manners there. ___ 1 ___? B: Sure. A: ___ 2 ___? B: Well, they think i...
【简答题】Quartz or fused silica is required for work in the _________ region (below 350 nm). Both of these substances are transparent throughout the visible and near-IR regions to about 3 μm wavelength.