题目

—Do you think the weather will be all right this summer? —No, ________ we’re lucky. The newspaper says it’ll be very hot anyway. A. if               B. though                C. unless              D. as 答案：C粗细、长度均相同的铜、铁、铝三根导线，它们的电阻A.铜导线最大B.铁导线最大C.铝导线最大D.三种导线一样大