Mary used to ________ to work, but she is used to ________ to work now.
⑴有一个角是直角的四边形是矩形;
⑵一组邻边相等的平行四边形是菱形;
⑶一组邻边相等的矩形是正方形;
⑷一组对边平行且相等的四边形是平行四边形.
其中真命题的个数是( )