【单选题】在尺寸为8m×9m×10m的混响室中测某材料的吸声系数。若空室混响时间为5s,铺上该材料10m2后,混响时间变为2s。则该种材料吸声系数约为( )。
【简答题】请将下面这段话翻译成英文: 可持续发展是20世纪80年代提出的一种新的发展观。这种模式要求在保护环境的条件下发展经济,既要满足当代的需求,又不能损害后代人的利益。它的核心思想是确保经济、资源和环境的协调发展,目的是让子孙后代享受充分的资源和良好的环境。可持续发展是中国的一项基本国策。目前中国正集中精力节能减排,加快资源节约型和环境友好型工业体系的建设,加大环境保护力度,提高生态文明(ecologi...
【简答题】[A] enhances [B] attaches [C] inserts [D] adds
【单选题】Cracks may be prevented from developing at the corners of welded plating inserts by ______.
C.
plug welding the corners
D.
slot welding the corners
【单选题】Ring groove inserts are occasionally used on aluminum alloy piston to_______.
A.
reduce the ring groove wear rate
B.
seal against crankcase vapors
C.
lessen the wear on aluminum part of the cylinder
D.
allow for the greater expansion rate of aluminum
【单选题】The author inserts Paragraph 19 and 20 in the story for the purpose of ______________.
A.
describing what NHC had done with Hurricane Camille
B.
providing evidence of the seriousness of natural disasters
C.
telling the reader how destructive Hurricane Camille was
D.
building a suspense about what would happen to the family