按除尘器的形式分为()和()电除尘器,管式电除尘器主要适用于()场合,板式电除尘器应用广泛。
参考答案:管式;板式;烟气量小的
(2013·南昌10所省重点中学二模)Mary ________ as a secretary in this company for twenty years and now she stays at home taking care of her own garden.
A.has served
B.had served
C.is serving
D.served
在数据仓库中存放的数据是为了适应数据的______处理要求而集成起来的。