句子成分解析1) Some teachers divide students into groups according

句子成分解析1) Some teachers divide students into groups according to how high their marks are.请问这句中的how high their marks are在全句中作什么成分?(2) 请问 etc.是什么的缩写?怎么读?(3) I should let you know ,that what the students need is knowledge but not necessarily high marks.请问该句中的副词 necessarily 在句中是起强调not 的,还是指"不必要的高分" (4) 请问"get too carried away"和"muse over"分别是什么意思?