Can you guess if they ________ to play basketball with us ? I think they’ll come if they _______ free .

A．come, are

B．will come , will be

C．will come , are

D．come , will be

一个等腰三角形的两边分别为3cm和4cm，则它的周长为______；若一个等腰三角形的周长是20cm，一边长是5cm，则另两边的长是______．