A widener is provided, including: a base, a pushing assembly and a driving assembly. The base includes an inner space, a first passage and a second passage which are communicated with one another, and the first passage is transverse to the second passage. The pushing assembly includes a first pushing board, a second pushing board and a linkage member. The first pushing board is positioned at the base. The linkage member is movably inserted within the second passage. The second pushing board comovably connected with the linkage member. The driving assembly includes a tube body, a driving member and a driving block. The tube body defines a driving space, and the driving block is movably received in the driving space. An end of the tube body is connected with the first passage and the driving space is communicated with the inner space.
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