1.A://// B:cleane r 2.A:How does he go to work?B:/// 3.A:What does your father do?B://////是未知项 写清

1.A://// B:cleane r 2.A:How does he go to work?B:/// 3.A:What does your father do?B://////是未知项 写清 4.Where does your uncle work?B:/// 5.A://// B:I am student.根据上句写下句或根据下句 ///是未知项 写清4B:5A:1.A://// B:cleane r 2.A:How does he go to work?B:/// 3.A:What does your father do?B:///4.Where does your uncle work?B:/// 5.A: The room is in a terrible mess,it ___ cleane;a、can’t have been b、shouldn’t have beenc、mustn’t have been d、wouldn’t have been please ()the dirty cup away and ()me a cleane one.填bring 还是take?为什么 r(A)+r(B)-n 证明R(A)+R(B)-R(AB) 1.The girls had a good time on the school trip The girls ____ ____ on the school trip 2.The science1.The girls had a good time on the school tripThe girls ____ ____ on the school trip2.The science teacher cleaned the bus yesterday afternoon 对cleane 证明r(A+B) 线性代数：设A为m×p矩阵,B为s×n矩阵,证明：1.r|A O|=r(A)+r(B) |O B|2.r|A C|>=r(A)+r(B) |O B| 指数运算性质的疑问1.a^r*a^s=a^(r+s) (a>0,r,s∈Q）.2.(a^r)^s=a^(r*s) (a>0,r,s∈Q）.3.(a*b)^r=a^r*b^r (a>0,b>0,r,s∈Q）.我觉得对于a b来说,就算是a0 1.设A={a,b,c},则A×A中的元素有几个（ ）2.公式p∧q一定不是（ ）A,合取范式 B,析取范式 C,主合取范式 D主析取范式3.设R是非空集合A上的关系,且R=R○R○R○R ,则（ ）A.R B.R○R C.R○R○R D.R○R○R○R A,B为4阶方阵r(A)=4,r（B)=3,A和B的伴随矩阵为A*,B*则r(A* B*)是前方证A*可逆省略.进而r(A*B*)=r(B*).由于BB*=|B|E=0,因而r(B)+r(B*)小于等于4.于是r(B*)4-r(B)=1.由于r(B)=3,因而|B|有一个非0的余子式Mij.由于 证明 r(A)+r(B)-n a b 属于R a(a+b) 怎么证明R(AB)>=R(A)+R(B)-N 线性代数 从矩阵A中划去一行得到矩阵B,求A,B秩的关系R(A)≥R(B)≥R(A)-1. a、b属于R |a|+|b| a,b属于R且a+b