单项选择题在逆流吸收过程中,操作液气比增大,操作线与平衡线之间的距离( )。 A、减小 B、增大 C、不变 D、不确定
单项选择题Filling blanks with the right indefinite or definite articles: Interactional competency is ______ ability to communicate with others. Piano is _____ type of musical instrument which consists with strings and keys. Culture is _____ set of features and variables that define a group of community.