用括号内所给单词的适当形式填空
（1）—Is Grace your aunt?
—Yes, ____ (her) is.
（2）Mike and Bob ____ (be) friends.
（3）His ____ (grandparent) are in Beijing.
（4）These are her ____ (sister).
（5）—Are ____ (this) your pencils?
—No. My pencils are not black.
