在带有活塞的有机玻璃筒底放置少量硝化棉，迅速压下活塞， 观察到硝化棉燃烧起来。关于这个实验，以下说法正确的是 （ ） A．
51. He made an _____________ (apologize) to me for hurting my feelings. 52. After a long _____________ (argue), he gave way. 53. He pretended _____________ (get) the result but wouldn’t tell us.
New technologies have made _____possible to turn out new products faster and at a lower cost. A. that B. this C. one D. it
如图，a的金属活动性在氢以前，b为碳棒，关于下列装置的说法中不正确的是( ) A．a极上发生还原反应，b发生氧化反应 B．碳棒上有气体逸出 C．电子流
Don’t lose heart. It won’t be long ___________ you catch up with others. A. since B. until C. as D. before
--- Are you familiar with the music ? --- Yes. There was a time _____ this kind of music was quite popular. A.when B.that C.with which D.about which
肌肉注射时，药液进入人体后经过的一般途径如图：其中①②③分别表示 A．组织液、血浆、淋巴
真核生物染色体中DNA遗传信息的传递与表达过程，在细胞质中进行的是 A.复制 B.转录 C.翻译 D.转录和翻译
