A:take u
B:take i
C:take o
D:take over
已知数列an,若点n,an(n∈N*)均在直线y-2=kx-5上,则数列an的前9项和S9等于( )
— You must _____ a letter to your mother tomorrow.
— Well, I will, Dad.
下列现象用分子理论解释正确的是 ( )