题干
During the Spring Festival, Li Lei got a red envelop with 500 yuan. He spent his lucky money on his hobbies. According to the following table, do you know how much he left?
Watched a movie in Wanda Cinema with some friends | 50 yuan/each |
Bought 3 story books | 20 yuan/each |
Bought 2 money stamps | 50 yuan/each |
Notes: one of his friends treated him when watching the movie | |
A：190
B：240
C：340
答案(点此获取答案解析）
C
6 H2O + 5N2，当各物质的浓度不随时间变化时，混合气体的体积为17L，则原混合气体中NO和 NH3的体积之比为