—Tommy looks so tall.
—That's right.Tommy is known as the tallest boy in our school.
A:wants to be
B:is famous as
C:used to be
若数列{an}的前n项和Sn=n2+1 则a1+a9等于( )
— Sorry. I returned it to the library just now. Maybe it is still ____.
估算(用计算器验算)
30×98≈____
33×8≈____
若存在实数x使|x﹣a|+|x﹣1|≤3成立,则实数a的取值范围是____