铅蓄电池总反应为PbO2+Pb+2H2SO4═2PbSO4+2H2O,下列关于铅蓄电池的说法正确的是
| A.在放电时,正极发生的反应是 Pb(s) +SO42―(aq)= PbSO4(s) +2e― |
| B.在放电时,该电池的负极材料是铅板 |
| C.在充电时,电池中硫酸的浓度不断变小 |
| D.在充电时,阳极发生的反应是 PbSO4(s)+2e―=" Pb(s)+" SO42―(aq) |
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 ks |
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 |