问题
选择题
—How unhappy your roommate looks!
—Yes, but he's not willing to tell me what it is ________ is troubling him.
A．what
B．which
C．as
D．that
答案
答案：D
选D 考查强调句型。分析句子结构可知，此处为特殊疑问句的强调句式，其结构为“特殊疑问词＋is＋it＋that＋从句”，又因强调句在句中作tell的宾语，应用陈述句语序。故选D。