to put flour, sugar, etc. through a sieve (= wire net shaped like a bowl) to break up large pieces

When the cake is cooked, sift some icing sugar over the top of it. 蛋糕做好后，在上面筛上一些糖粉。

to make a close examination of all the parts of something in order to find something or to separate what is useful from what is not

The police are sifting the evidence very carefully to try and find the guilty person. 警察在非常仔细地检查证据，试图找出罪犯。

After my father's death, I had to sift through all his papers. 父亲去世后，我必须查看整理他的所有文件。

The police are trying to sift out the genuine warnings from all the hoax calls they have received. 警方试图从他们接到的各种恶作剧电话中分辨出真正的报警电话。