翻译:她通常在年级排名十几或二十几,有一两次掉出前30位,

She often ranks from ten to twenty or twenty to thirty in the whole grade except a ranking from twenty to thirty once or twice 相信我

She usually was between more than the tenth
and twentith places or so in grade,who was out
of top-thirty positon occasionally.

Generally speaking, she grades in the position which is some bit more than 10 or 20, and just by one or two time did she fell out the 30th grade position.