下列混合物的物质的量一定时，组内各物质按任意比混合，完全燃烧时耗O2的量不变的是
| A．甲烷、甲醇、甲醛 |
| B．乙炔、苯、1，3－丁二烯 |
| C．丙烯、2－丁烯、环已烷 |
| D．乙醇、乙烯、丙烯酸（CH2=CH－COOH) |
I’m sure that your letter will get______ attention. They know you’re waiting for the reply. 
| A．continued | B．immediate | C．careful | D．general |
All the dishes in this menu, ______ otherwise stated, will serve two to three people. 
| A．as | B．if | C．though | D．unless |
The children loved their day trip, and they enjoyed the horse ride ______.
| A．most | B．more | C．less | D．little |
I can’t leave. She told me that I ______ stay here until she comes back.
| A．can | B．must | C．will | D．may |
—— Do you mind my opening the window? It’s a bit hot in here.
—— ______ , as a matter of fact
| A．Go ahead | B．Yes, my pleasure |
C．Yes, I do | D．Come on |