“…Crowdsourcing is a special sourcing model in which pieces of micro-tasks are distributed to a pool of online workers. It has become a popular research topic in the recent decades because of its widely commercial and academic adoption in areas, such as machine learning [22,29,47,49,56], computer vision [14,55], medical healthcare [25,30,45], and graph mining [6,7,42,48,50], and so on. Modern machine learning tools such as deep models require massive amount of labeled data.…”