例句1：Xiangxiang did his homework and Tyger went out shopping.

例句2：Xiangxiang was doing his homework and Tyger was going out shopping.

例句3：When Xiangxiang was doing his homework， Tyger was going out shopping.

例句4：When Xiangxiang was doing his homework， Tyger went out shopping.

四句的场景用法:

1 爸爸问妈妈，翔翔和Tyger刚干什么了？妈妈说，翔翔做作业，Tyger出去买东西了。

2爸爸问妈妈，翔翔和Tyger刚刚在干什么？妈妈说，翔翔在做作业，Tyger在购物。

3爸爸问妈妈，翔翔刚做作业时，Tyger在干嘛？妈妈说，翔翔做作业时，Tyger在购物。

4爸爸问妈妈，翔翔做作业的时候，Tyger干嘛去了？妈妈说，翔翔做作业的时候，Tyger购物去了。