将NaClO3和Na2SO3按物质的量比2：1加入烧瓶中，再滴入少量H2SO4溶液并用水溶解、加热，产生棕黄色气体X，反应后测得NaClO3和Na2SO3恰好完全反应。则X为（ ）
A．ClO2 B．Cl2O C．Cl2 D．Cl2O3
My friend showed me round the town, ______ was very kind of him. 
| A．which | B．that | C．where | D．it |
They use computers to keep the traffic _______ smoothly.
| A．being run | B．run | C．to run | D．running |
If you leave the club, you will not be_____back in .
| A．received | B．admitted | C．turned | D．moved |
What I need is_____ book that contains ______ABC of oil painting.
| A．a; 不填 | B．the; 不填 | C．the; an | D．a ; the |
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 |