(x2+y2)2﹣4(x2+y2)﹣5=0,则x2+y2的值为( )
A:5
B:﹣1
C:5或﹣1
D:无法确定
I like this pair of boots, can I try ____on? (it)
关于声音的产生与传播,下列说法正确的是()
计数器从右边起,第一位是____位,第二位是____位,第三位是____位。
-- Would you like to play football after school?
-- ________. I have a lot of homework to do.