单选题I had just taken a&n

问题补充：

单选题Ihadjusttakenabiteofmyhotdog________Iheardafamiliarvoiceyellingatmefromacrossthecrowdedschoolyard.A.beforeB.whileC.sinceD.when

答案：

D解析考察连词。该句为固定句型，sb had just done sth when sb did sth意为某人刚做完某事，突然……