单项选择题 We listened dumb-struck, full of ______ to the shocking details of the corruption of the ex-president of the company.

单项选择题 Hydrocarbons, ______ by engine exhausts, react with nitrogen oxides in the presence of sunlight to form complex toxic gases.

单项选择题 It is ______ understood by all concerned that the word no one who visits him ever breathe a syllable of in his hearing will remain forever unspoken.