拉抽屉是平移现象,拧螺丝是旋转现象.______.
拉抽屉是平移现象,拧螺丝是旋转现象,所以题干说法正确.
故答案为:正确.
在公差为3的等差数列{an}中,若a1,a3,a4成等比数列,则S6等于( )
A.27
B.-18
C.-27
D.24
What can you see?[ ]
A. I can see my teacher.
B. This is our classroom.