下面三个英语句子里每句都有一处错误，请帮我找出并改正，谢谢

Question

1.who's hand is this？

2.Mary's picture have ten stars.
3.how many computer do you have?

Answer 1

我觉得：
第一句：’s=is，后面又有一个is，那么一个句子就有两个谓语动词（系动词），且没有连接词，改法：把who‘s改为whose。
第二句：picture，是单数，have改为has
第三句：computer改为复数的computers

Answer 2

1.whose，who‘s是who is的缩写，并不是直译为谁的，而whose才是谁的，就如同his代表他的
2.has，因为主语是picture 不可数
3.computers ，many修饰可数名词，要加名词复数本回答被提问者采纳

Answer 3

1who's 应为whose
2have应为has
3computer要加“s”

Answer 4

Whose hand is this?
Mary's picture has ten stars.
How many computers do you have?

Answer 5

1、Whose hand is this？
2、There are ten stars in Mary's picture.
3、How many computers do you have？