[word=is] [lemma=□] □
[word=is] [lemma=usually] □
[word=is] [lemma=focus] □
The aldolization can be catalyzed by acids or bases , but base catalysis is usually preferred . Otherwise stated , those inventions relating to the excavating art , including power scoops , shovels or the like in which movement is imparted to such scoops or shovels subsequent to or in addition to those movements deemed necessary to complete an excavating operation , which additional movement is usually for transporting the excavated material to a disposal point , are considered to include such handling of the excavated material as will provide a basis for classification in this class ( 414 ) . Emphasis on aeronautical themes is usually preferred . The injector is usually constructed of plastic , which makes it resistant to most chemicals . The reaction occurs rapidly and often dramatically , and is usually unanticipated .