用三线-八线译码器74LS138和辅助门电路实现逻辑函数<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202003/c871492b27384497a59d367211b93efb.png" >，应：（） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202003/37b75181b0ad4fba92ee10f87ffa0bbb.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202003/453b2c724d1d4d41898e10c9ba036a39.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202003/2c10ee737f77406fa0457e0f02318515.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202003/9cbe3266526b4e8eab204cf96440be55.png" >

下列几个方程，表示质点振动为“拍”现象的是：（） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202003/9667dbfe77314804a8c29f40c44cd0eb.png"> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202003/c7bc921fc7c04ce6832fea3a190e7d8d.png"> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202003/87e37e83ce244721905379b745be2bba.png"> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202003/026e1391030345459a10867db4150d25.png">

钢号Q345A中的345表示钢材的（）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202003/af6807e52a454663a6eaf1728a03a050.png" >值 B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202003/3cf447dcca4b4032bf4df7ef7b7a8f7f.png" >值 C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202003/390a6cad6f4746668ba550f409ead899.png" >值 D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202003/f0782fccfc8047bb9aea1b0934a4dfed.png" >值

下列羰基化合物分子中，既存在σ-π超共轭效应，又存在π-π共轭效应的是（） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/b037ba3cc4b845c6a7a89933bf438d98.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/46bc3c9d231349e091ffb48341727085.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/9d5bb2934ef240349846c4a3dcac3f2f.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/abecafc7ca9f4a83bd3c839cb61c8b21.png" >

已知柠檬酸盐、顺乌头酸盐和水在298K时的标准生成吉布斯自由能<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202009/230323b775e24e9ebffb1a4330307a16.png" />则298K时反应柠檬酸盐=顺乌头酸盐+水的平衡常数KΘ为（ )。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202009/fe98bf07bba54e0bb73a07ace3605614.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202009/ee289691e7a94985969b986f4c9647e4.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202009/b6fea00840e04590ab15c2e23d578e3c.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202009/b1024622af914336ae597c37d848d3af.png" />