正方形手帕的边长是20厘米，手帕的周长是______厘米．
20×4=80（厘米），
答：手帕的周长是80厘米．
故答案为：80．
It is good ________ for an Arab to stand ________ his friend when they are talking.
A．manners; close to
B．manner; close to
C．manners; closely to
D．manner; closed to
关于泪小管炎的临床表现，下列哪项不正确
A．眼红、溢泪、眼分泌物
B．压迫泪小点有分泌物
C．摘除泪囊后，从泪小点挤压无黏性分泌物
D．常由沙眼衣原体、放线菌等引起
E．结膜充血
