Perhaps you should try some spelling variations:
class teachers » classroom teachers
class teaching » class teacher, classroom teaching
china roberto » chang roberto, change roberto, asia roberto
sein time » sein die, sein eine, den time
roberto n » robert _, robert e, robert j
tan yang » dan yang, tan ying, tan yong
fan ying » fan xing, ran ying, tan ying

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((tan yang) OR (fan ying)) sein time ((class teaching) OR (class teachers)) china roberto n ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tan yang) or (fan ying)) sein time ((class teaching) OR (class teachers)) china roberto n ;~".
• Adding a wildcard symbol may retrieve word variants: ((tan yang) or (fan ying)) sein time ((class teaching) OR (class teachers)) china roberto n ;*.