在体积为VL的密闭容器中通入amolNO和bmolO2反应后，容器内氮原子和氧原子数之比是（ ）
| A．a∶b | B．a∶2b | C．a∶(a+2b) | D．a∶(2a+2b) |
Jenny nearly missed the flight______ doing too much shopping.
| A．as a result of | B．on top of | C．in front of | D．in need of |
The CDs are on sale! Buy one and you get ______ completely free. 
| A． | other | B． | others | C． | one | D． | ones |
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 |