1.We saw the boy is swimming in the water yesterday.
改为：We saw the boy 【swim\simming】 in the water yesterday.
原因：see sb. do\doing sth.
2.Lucy and Lily are twins,they look same.
改为：Lucy and Lily are twins,they look 【the】 same.
原因：same前一般要加the
3.How many apples trees are there in the garden?
改为：How many 【apple】 trees are there in the garden?
原因：这里的意思应该是苹果树,所以apple后不用加s
4.She showed her photos for us wen minutes ago.
改为：She showed her photos 【to】 us minutes ago.（有两处错误?还是你打错了?是不是最后应该是ten minutes ago）
原因：show sth. to sb
5.He can’t makes model ships.
改为：He can’t 【make】 model ships.
原因,can是情态动词,情态动词后应该加动词原形