题目

—David, are you listening to me? —Sorry, sir. I ________ of the lecture I attended yesterday. A . have thought B . was thinking C . am thinking D . thought 答案：B六人按下列要求站一横排，分别有多少种不同的站法？（l）甲不站两端；（2）甲、乙必须相邻；（3）甲、乙不相邻；（4）甲、乙之间间隔两人；（5）甲不站左端，乙不站右端．