1．与有相同图象的一个函数是                                         (     )

          A.                           B.

          C.            D.

2. 若的定义域为则函数的定义域为            (     )

A.          B.               C.              D.

3. 函数的定义域为                                    (     )

A.           B.           C.            D.

4. 若函数的值域也为,则的值为               (     )

A.1或3            B.1或          C.             D. 3

5. 已知且,则的值为                             (      )

A.  2或          B.2              C.               D.

6. 当时,下列不等式中成立的是                                  (      )

         A.                    B. 

 C.                    D.