沥青马蹄脂碎石混合料应采用针入度较大,粘度较小的沥青,最好采用性能良好的聚合物改性沥青,沥青的用量不小于6.2%。()
You should spend no more than 20 minutes on this task. You borrowed some books from your school or college library. Unfortunately you have to go away to visit a sick relative and cannot return the books in time. Write a letter to the library. Explain what has happened and tell them what you want to do about it. You should write at least 150 words. You do NOT need to write your own address. Begin your letter as follows: Dear______,
对岩体坡面进行灌缝或勾缝时,应先将缝内冲洗干净。()
三相桥式全控整流电路是两个三相半波可控整流电路串联的结果。()