某中学九年级舞蹈兴趣小组8名学生的身高分别为(单位:cm):168,165,168,166,170,170,176,170,则下列说法错误的是( )
已知等腰三角形的一边长等于4cm,另一边长等于9cm,则此三角形的周长为 ____cm.
Some exchange students _______ with their host families this time yesterday.