I just wanna figure the problem out in the answer given by sky6363. "qíng nǐ hǎo hāo duì tā" when two word have the same pronunciation 3th, we'd like to change the pronounciation of the first word to 2ed tones-"qǐng to qíng",but, if these words conbine to a single word, we usually pronounce the second word with 1st tones-"hǎo to hāo"-with lighter accent.

(Sorry for my foult ..) for example, 1.there were no single "hui" in an usual sentence, it must adding a place noun. "shenme shihou(What’s the time) hui jia(go home)?" 2.the "lai" in "huilai" means a status that sb. or sth. reach someplace NEAR to the speaker.(huilai is a mini sentence——a vt. with a adv.) ps:"huiqu" is little different with "huilai","qu" in "huiqu" means a status that sb. or sth. reach someplace AWAY from the speaker pps:the word "hui" has so many meanings in Chinese, not only "to return". :P

for example, 1.there were no single "hui" in an usual sentence, it must adding a place noun. "shenme shihou(What’s the time) hui jia(go home)?" 2.the "lai" in "huilai" means a status that sb. or sth. reach someplace NEAR to the speaker.(huilai is a mini sentence——a vt. with a adv.) ps:"huiqu" is little different with "huilai","qu" in "huiqu" means a status that sb. or sth. reach someplace AWAY from the speaker pps:the word "hui" has so many meanings in Chinese, not only "to return". :P