In 1803 the United States purchased Louisiana from _____.

AutoCAD2004图形文件和样板文件的扩展名分别是（）。 A: DW B: DWG C: DW D: DWT E: BM F: BAK G: BA H: BMP

十六进制数1AF转换成八进制数是（ ） A: 657 B: 567 C: 887 D: 697

In 1803, President Jefferson negotiated the purchase of Louisiana from Mexico.

设A为m×n矩阵，B为n×m矩阵，且m＞n，则必有() A: |AB|=0 B: |BA|=0 C: |AB|=|BA| D: ||BA|BA|=|BA||BA|

下列设置打开文件对话框OpenFileDialog1的Filter属性正确的是_________。 A: OpenFileDialog1.Filter=Pictures(*.Bmp)|*.Bmp B: OpenFileDialog1.Filter=["Pictures(*.Bmp)"|"*.Bmp"] C: OpenFileDialog1.Filter="Pictures(*.Bmp)|*.Bmp" D: OpenFileDialog1.Filter={Pictures(*.Bmp)|*.Bmp} E: OpenFileDialog1.Filter=(Pictures(*.Bmp)|*.Bmp)

以下正确的语句是＿＿＿＿。 A: OpenFileDialog1.Filter=All Files|*.*|Pictures(*.Bmp)|*.Bmp B: OpenFileDialog1.Filter="All Files"|"*.*"|"Pictures(*.Bmp)"|"*.Bmp" C: OpenFileDialog1.Filter="All Files|*.*|Pictures(*.Bmp)|*.Bmp" D: OpenFileDialog1.Filter={All Files|*.*|Pictures(*.Bmp)|*.Bmp}

以下正确的语句是____。 A: CommonDialog1.Filter= All Files|*.*|Pictures(*.Bmp)|*.Bmp B: CommonDialog1.Filter= "All Files"|"*.*"|"Pictures(*.Bmp) "|"*.Bmp" C: CommonDialog1.Filter= "All Files|*.*|Pictures(*.Bmp)|*.Bmp" D: CommonDialog1.Filter= {All Files|*.*|Pictures(*.Bmp)|*.Bmp}

国际网球联合会成立于 A: 1903 B: 1803 C: 1913 D: 1923

霍尔效应哪一年发现的？ A: 1881 B: 1879 C: 1803 D: 1831