【单选题】Which of the following is NOT described in the passage?
A.
Whales migrate to breed and give birth to their young.
B.
Whale-watching in Boston in summer is attracting.
C.
Seals breed in the north before migration.
D.
Reindeer feed on grass.
【简答题】16 的算术平方根是 ; 的算术平方根是 ; 81 的算术平方根是 ; 的算术平方根是 ,
【简答题】的平方根是( );81的算术平方根是( ); 的平方根是( )。
【简答题】2 1 4 的算术平方根是______,9 2 的算术平方根是______, 81 的算术平方根是______.