例如There( )an apple on the table.一定要填is吗?如果填was行吗?请各位赐教.在没有上下文提示的情况下一般用什么时态？还是什么都可以用？

There is an apple on the There is an apple in his hand there is an apple in the tree . There is an apple and two pens There are an apple and two pens 哪个对 there ia an apple in the basket 划线提问an There are an apple and an orange对吗? there is an apple.分析结构 到底there是主语还是Apple是主语 there is an apple on the table 改为复数形式 There is an apple in my hand.(变成同义句) There was an apple on the table复数句 There is an apple on the tree.(改为复数） there ( ) an apple and some oranges on the table is there an apple on the table?否定回答 Is there in tree apple an the连词成句 is there an apple on the table.否定句 There is an apple on the table.否定句 There is an apple in the box.变复数句 There is an apple in the box.改成否定句