lily and lucy are good friends ,这句话有错吗,为什么不是friend然后为什么不是is.还有其他这样be动词容易弄错的情况吗

Lucy and Lily are twins.同义句转换：Lucy ----- ----- ----- ----- Lily. where are还是is lucy and lily their 什么 are lucy and lily The twins’ name are Lucy and Lily ______ Lucy and Lily go home at seven?A.Do B.Does C.Is D.Are Lily and Lucy will go to a shop to buy something 和Lily and Lucy are going shopping with their fathe lily and lucy,sister,not,are.连词成句lily and lucy,sister,not,are.(.) 改写句子使句意不变They are Lily and Lucy.改写：( ) ( )are Lily and Lucy These are( )friends A.Lucy's and Lily's B.Lucy and Lily C.Lucy and Lily's D.Lucy's and Lily Here is lucy and lily 还是 Here are lucy and lily.急 Who is Lily and Lucy?还是Who are Lily and Lucy? lucy and lily is twins 还是Lucy and lily are twins请问哪句话对? Lucy and Lily are twins=Lucy and Lily __ __ __ __help Lucy and Lily are his sisters 就画线部分提问 划线部分是 Lucy and Lily The desks are ________.A.Lily's and Lucy's.B.Lily and Lucy's lucy and lily are talking some photos 对划线部分提问(lucy and lily) 请问括号内填什么,These are （ ）bags.A.Lily and Lucy's B.Lily's and Lucy's C.Lily and LucyD.Lily's and Lucy Lucy and Lily are twins.they are the s___age.