My brothers were wathering some flowers at this time yestday. 怎么改

My brothers were wathering some flowers at this time yestday. 怎么改
My brothers were wathering some flowers at this time yestday. 怎么改

My brothers were wathering some flowers at this time yestday. 怎么改
----------My brothers were watering some flowers this time yesterday.

没有错误吧。我兄弟昨天的这个时候在浇花。

去掉at就对了。
this time 这次，这回
表达的意思不局限于时间了，是与以前(last time)相比较
如 He defeated me last time, but I will win this time.(他上次打败我了，不过这次赢的人是我）
没有at this time的用法

at接的不应该是时间，去掉at