1.Helen do not absent today.
do 改为 is
2.My brother not at school.
not 前面加 is
3.I can see some birds on the tree.
on 改为 in
4.We have a breakfast at six thirty.
去掉a
5.What colour is Kate‘s trousers?
is 改为 are
祝你学习进步,更上一层楼!(*^__^*)