1 [T] to pass flour, sugar or a similar substance through a SIEVE in order to remove any lumps 筛；滤: to sift flour/sugar 筛面粉╱糖

2 [I,T] sift (through) sth to examine sth very carefully 仔细检查；详细审查: It took weeks to sift through all the evidence. 细查这些证据花了多个星期。