知：C(s)＋H2O(g)＝CO(g)＋H2(g) △H＝a kJ/mol C(s)＋O2(g)＝2CO(g) △H＝－220 kJ/mol H－H、O＝O和O－H键的键能分别为436、496和462 kJ/mol，则a为 A．－332
某新型燃料电池能以乙烯为原料制备乙醛并获得电能，工作原理如图所示。下列有关说法正确的是 A.a 电极为正极 B．电子移动方向：a 电极→磷酸溶液
下面语段横线处应填入的词语，最恰当的一组是 我们都知道，现在“种花”已经不能呢个仅凭劳动力和气候来___收益了。如果没有优良的花卉品种、先
He's never been here before, ________？ A.is he B.isn't he C.has he D.hasn't he
能为细胞提供与呼吸作用有关的酶的细胞器是 A.高尔基体 B.溶酶体 C.线粒体 D.核糖体
Topping the class academically was certainly an advantage. Studying was a breeze for Nigel. The reward was certainly incomparable to the little effort that he had to put it. It begin when he was sele
--- Mum, I don’t want to take the medicine． --- Oh dear, you should know that good medicine for health ____ to the mouth． A．tastes bitter B．tastes bitterly C．is tasted
（2013衡水中学调研）如图所示是某同学在做匀变速直线运动实验中获得的一条纸带． (1)已知打点计时器电源频率为50 Hz，则纸带上打相邻两点的时间
则不等式
的解集为 （ ）
B．
D．
