—Not ______. Some students still lose themselves in playing computer games every day.
A:yet, yet
B:already, already
C:yet, already
C3N4是一种新型材料,它的硬度比金刚石还大,可用作切割工具。在C3N4中C元素的化合价为+4,则N元素的化合价是 ____。
读一读,连线。
① ____ a. - Goodbye. - Goodbye.
② ____ b. - Hello! - Hi!
③ ____ c. - Good morning, Miss Li. - Good morning, Tim.
结合如图所示装置回答问题:
图一中,对①、②、③城市的气候特征的叙述正确的是( )