— Michael was late for Mr. Smith’s oral class this morning. — _________? As far as I know, he never came late to class. A. How come B. So what C. Why not D. Guess what 答案:A1938——1944年,我国科技人员在大后方注册的专利共431件,比此前20年全国的总和增长了157%,其中机器、电器、交通工具、化学药品类居多。形成这一现象的主要原因是
[ ]A.科技人员的内迁B.军工企业的激增C.民营工业的发展D.战时需求的刺激