改错1.The teacher looked angry at the students 2.They must have arrived till now
问题描述：
改错1.The teacher looked angry at the students 2.They must have arrived till now
答
1.looked改成is
2.till去掉
答
1.把angry改为angrily，动词应该用副词修饰；
2.把till改by,must have done是对过去事情的猜测，till now是指现在。
答
1、 angry 改为angrily,修饰动词 look at.
2.arrived 改为been.
答
1.把at改为with
2.把have改为be