This is the tree and these are the flowers.
句子为陈述句。根据句中指示代词this和these以及and,可知句子为并列句。故this或these都可置于句首,this 后需跟be动词单数is及名词单数,句中没有不定冠词a,故用the tree,these为复数,其后需用be动词复数are,及可数名词复数flowers. 中间用and连接。故本题答案为:This is the tree and these are flowers. / These are flowers and this is the tree.