【简答题】74LS138 译码器的地址译码输入端有 个
【单选题】—Did you forget about my birthday? —________ I've booked a table at Michel's restaurant for this evening. [ ]
【单选题】—Did you forget about my birthday? —____________ I’ve booked a table at Michael’s restaurant for this evening.
【单选题】. —We have booked a room for today and tomorrow. — _________, sir.
【单选题】已知光在真空中的传播速度是 3 × 10 8 m/s ,在尖晶石中的传播速度为 174419km/s ,尖晶石的折射率是
【简答题】光在真空中的传播速度为多少?若太阳和地球的平均距离为1.5×10 8 km,则太阳光照到地面要用多长时间?