问题
选择题
Would you please _ _ the window? It's too cold outside.
[ ]A. open
B. opening
C. not open
D. not to open
答案
答案:C
Would you please _ _ the window? It's too cold outside.
[ ]A. open
B. opening
C. not open
D. not to open
答案:C
若对表3-1按 (12) 进行运算,可以得到表3-2。
条 形 码 | 商 品 名 | 价 格 |
01020210 | 牙刷 | 3 |
01020211 | 毛巾 | 10 |
01020212 | 毛巾 | 8 |
01020213 | 铅笔 | 0.5 |
02110200 | 钢笔 | 8 |
条 形 码 | 商 品 名 | 价 格 |
01020211 | 毛巾 | 10 |
01020212 | 毛巾 | 8 |
02110200 | 钢笔 | 8 |
A.σ条形码=’01020211’∨’02110200’(表3-1)
B.σ商品名=’毛巾’∨’铅笔’(表3-1)
C.σ价格≥8(表3-1)
D.π1,2,3(表3-1)