A:an+ap=am+aq
B:an-am=ap-aq
C:an-ap=am-aq
D:an+am=ap+aq
--How old ____________ your cat?
--I think ____________ one.
1分硬币、1角硬币、5角硬币的厚度大约是____ 毫米.电话卡、银行卡的厚度大约是____ 毫米.
等差数列{an}中
等比数列{bn}中
a3+a4=a2+a5
b3•b4=b2•b5
a1+a2+a3+a4+a5=5a3
____
Microsoft ended support for Windows XP after April 8, which _______a major operating system for some Chinese computer users, and advised users to upgrade to Windows 8.1.