这家动物园是四年前开的.它开了已有四年了.Thatzoo()fouryearsago,it()(）（）（）fouryears.当老师离开的那一段时间,我们在大声讨论.Whiletheteacher()(),we()（）loudly.当老师离开的那一

Question

这家动物园是四年前开的.它开了已有四年了.
That zoo ( ) four years ago ,it ( )( ）（ ）（ ）four years.
当老师离开的那一段时间,我们在大声讨论.
While the teacher ( )( ),we ( )（ ）loudly.
当老师离开的那一刻,我们都在做作业.
When the teacher ( ),we ( )( ) our homework.

Answer 1

这家动物园是四年前开的.它开了已有四年了.
That zoo ( was opened ) four years ago , it (has )(been)（open）（for）four years.
当老师离开的那一段时间,我们在大声讨论.
While the teacher ( was )( away ),we (were)（discussing）loudly.
当老师离开的那一刻,我们都在做作业.
When the teacher ( left ),we ( were )(doing ) our homework.