sentence1: If you are a Chinese citizen of the HKSAR and hold a valid Mainland China home return permit -LRB- 港澳居民來往內地通行證 -RRB- for how long can you enter and remain in Mainland China ? Is there any time limitation at all ?
sentence2: If you are a Chinese citizen of the HKSAR and hold a valid Mainland China home return permit -LRB- 港澳居民來往內地通行證 -RRB- , can you enter Mainland China without it ?