A:wanted; wrote
B:had wanted; was writing
C:have wanted; wrote
D:wanted; have been writing
解方程:
下图(单位:厘米)中,正方形的周长和面积各是多少?
在家庭电路中,导线相互连接处往往比别处更容易发热,甚至引起火灾。原因是连接处( )