What day was yesterday?

昨天是星期几？

I'm not sure what time I'm coming back.

我不肯定我什么时间回来。

We used to have a lot of interesting friends.

我们过去常有很多有趣的朋友。

There used to be a grocery store on the corner.

过去在角落上有一个杂货店。

Will it be convenient for you to explain your plans to him?

你向他解释计划将是方便的吗？

The doctor said I look pale.

医生说我看起来很苍白。