【单选题】Watch-making and tourism are the chief __of that country.
【简答题】 observations of ocean like observing an antique watch.
【多选题】两原子轨道组合形成分子轨道时,必须符合的组合原则有
【多选题】两原子轨道组合形成分子轨道时,必须符合的组合原则有:
【单选题】Watch-making and tourism are the chief __________ of that country.
【单选题】Television lets us see history in the making. We can watch sports, political debates, trials and even wars ________.
【单选题】—What do you usually do on weekends? —I usually ______, because I like making friends. [ ]
【简答题】While my mother ______ (watch) TV, I was a kite.
【简答题】用价键理论和分子轨道理论解释N2和F2分子的结构。首先要清楚组成分子的原子的核外电子构型,再根据两种理论的观点解释其分子结构。价键理论的主要观点是:含有自旋方向相反的未成对电子的原子相互接近时,可形成稳定的化学键,共价键有饱和性和方向性..分子轨道理论的主要观点是:原子轨道形成分子轨道时必须符合对称性原则、最大重叠原理和能量相近原则,有几个原子轨道就可以形成几个分子轨道。