http://www.hdb.gov.sg/fi10/fi10321p.nsf/w/BuyResaleFlatConditionsafterpurchase?OpenDocument
刚刚在HDB找到的链接，根据现在的政策先买组屋再买condo，没关系。
但是30 August 2010实施的新政策：
If your resale application is submitted on or after 30 August 2010, you, your spouse, co-applicants and any occupiers listed in the resale application must dispose of any interest in any private residential property within six months from the completion of the purchase of the resale flat.
也就是说，我爸妈要把中国的房子在6个月之内卖掉。这个也太不方便了。